diff --git a/docs/api-v1.md b/docs/api-v1.md
index f428b6c3a67..040279ae1bc 100644
--- a/docs/api-v1.md
+++ b/docs/api-v1.md
@@ -587,6 +587,8 @@ Base endpoint is: `/ocs/v2.php/apps/spreed/api/v1`
 * `user_removed` - {actor} removed {user} from the conversation
 * `moderator_promoted` - {actor} promoted {user} to moderator
 * `moderator_demoted` - {actor} demoted {user} from moderator
+* `guest_moderator_promoted` - {actor} promoted {user} to moderator
+* `guest_moderator_demoted` - {actor} demoted {user} from moderator
         
 ## Guests
 
diff --git a/js/app.js b/js/app.js
index 1bf9c440294..e9dd7f24212 100644
--- a/js/app.js
+++ b/js/app.js
@@ -33,6 +33,7 @@
 		USER: 3,
 		GUEST: 4,
 		USERSELFJOINED: 5,
+		GUEST_MODERATOR: 6,
 
 		/* Must stay in sync with values in "lib/Room.php". */
 		FLAG_DISCONNECTED: 0,
@@ -373,13 +374,15 @@
 				id: 'participantsTabView'
 			});
 
-			this.signaling.on('participantListChanged', function() {
+			this._participantsListChangedCallback = function() {
 				// The "participantListChanged" event can be triggered by the
 				// signaling before the room is set in the collection.
 				if (this._participants.url) {
 					this._participants.fetch();
 				}
-			}.bind(this));
+			}.bind(this);
+
+			this.signaling.on('participantListChanged', this._participantsListChangedCallback);
 
 			this._participantsView.listenTo(this._rooms, 'change:active', function(model, active) {
 				if (active) {
@@ -389,6 +392,15 @@
 
 			this._sidebarView.addTab('participants', { label: t('spreed', 'Participants'), icon: 'icon-contacts-dark' }, this._participantsView);
 		},
+		_hideParticipantList: function() {
+			this._sidebarView.removeTab('participants');
+
+			this.signaling.off('participantListChanged', this._participantsListChangedCallback);
+
+			delete this._participantsListChangedCallback;
+			delete this._participantsView;
+			delete this._participants;
+		},
 		/**
 		 * @param {string} token
 		 */
@@ -666,6 +678,18 @@
 				// in the public share auth page).
 				this.activeRoom = new OCA.SpreedMe.Models.Room({ token: this.token });
 				this.signaling.setRoom(this.activeRoom);
+
+				this.listenTo(this.activeRoom, 'change:participantType', function(model, participantType) {
+					if (participantType === OCA.SpreedMe.app.GUEST_MODERATOR) {
+						this._showParticipantList();
+						// The public page supports only a single room, so the
+						// active room has to be explicitly set as it will not
+						// be set in a 'change:active' event.
+						this._participantsView.setRoom(this.activeRoom);
+					} else {
+						this._hideParticipantList();
+					}
+				});
 			}
 
 			this._registerPageEvents();
diff --git a/js/views/callinfoview.js b/js/views/callinfoview.js
index a1d98c28c0f..7d6dcab1747 100644
--- a/js/views/callinfoview.js
+++ b/js/views/callinfoview.js
@@ -44,8 +44,10 @@
 		'	</div>' +
 		'{{#if canModerate}}' +
 		'	<div class="share-link-options">' +
+		'		{{#if canFullModerate}}' +
 		'		<input name="link-checkbox" id="link-checkbox" class="checkbox link-checkbox" value="1" {{#if isPublic}} checked="checked"{{/if}} type="checkbox">' +
 		'		<label for="link-checkbox" class="link-checkbox-label">' + t('spreed', 'Share link') + '</label>' +
+		'		{{/if}}' +
 		'		{{#if isPublic}}' +
 		'			<div class="clipboard-button"><span class="button icon-clippy"></span></div>' +
 		'			<div class="password-button">' +
@@ -88,6 +90,7 @@
 				isGuest: this.model.get('participantType') === 4,
 				isInCall: (this.model.get('participantFlags') & OCA.SpreedMe.app.FLAG_IN_CALL) !== 0,
 				canModerate: canModerate,
+				canFullModerate: this._canFullModerate(),
 				isPublic: this.model.get('type') === 3,
 				showShareLink: !canModerate && this.model.get('type') === 3,
 				isDeletable: canModerate && (Object.keys(this.model.get('participants')).length > 2 || this.model.get('numGuests') > 0)
@@ -235,6 +238,10 @@
 		},
 
 		_canModerate: function() {
+			return this._canFullModerate() || this.model.get('participantType') === 6;
+		},
+
+		_canFullModerate: function() {
 			return this.model.get('participantType') === 1 || this.model.get('participantType') === 2;
 		},
 
diff --git a/js/views/participantlistview.js b/js/views/participantlistview.js
index 1980c92a556..353ced662af 100644
--- a/js/views/participantlistview.js
+++ b/js/views/participantlistview.js
@@ -35,6 +35,7 @@
 			' {{name}}' +
 			'{{#if participantIsOwner}}<span class="participant-moderator-indicator">(' + t('spreed', 'moderator') + ')</span>{{/if}}' +
 			'{{#if participantIsModerator}}<span class="participant-moderator-indicator">(' + t('spreed', 'moderator') + ')</span>{{/if}}' +
+			'{{#if participantIsGuestModerator}}<span class="participant-moderator-indicator">(' + t('spreed', 'moderator') + ')</span>{{/if}}' +
 			'{{#if inCall}}<span class="icon icon-video"></span>{{/if}}' +
 		'</a>'+
 		'{{#if canModerate}}' +
@@ -48,7 +49,7 @@
 			'</div>'+
 			'<div class="popovermenu bubble menu">'+
 				'<ul class="popovermenu-list">'+
-					'{{#if participantIsModerator}}' +
+					'{{#if canBeDemoted}}' +
 					'<li>' +
 						'<button class="demote-moderator">' +
 							'<span class="icon icon-star"></span>' +
@@ -56,7 +57,7 @@
 						'</button>' +
 					'</li>' +
 					'{{else}}' +
-						'{{#if participantIsUser}}' +
+						'{{#if canBePromoted}}' +
 						'<li>' +
 							'<button class="promote-moderator">' +
 								'<span class="icon icon-rename"></span>' +
@@ -108,10 +109,19 @@
 				});
 			},
 			templateContext: function() {
+				var isSelf = false,
+					isModerator = false;
+				if (OC.getCurrentUser().uid) {
+					isSelf = this.model.get('userId') === OC.getCurrentUser().uid;
+					isModerator = OCA.SpreedMe.app.activeRoom.get('participantType') === OCA.SpreedMe.app.OWNER ||
+						OCA.SpreedMe.app.activeRoom.get('participantType') === OCA.SpreedMe.app.MODERATOR;
+				} else {
+					isSelf = this.model.get('sessionId') === OCA.SpreedMe.app.activeRoom.get('sessionId');
+					isModerator = OCA.SpreedMe.app.activeRoom.get('participantType') === OCA.SpreedMe.app.GUEST_MODERATOR;
+				}
+
 				var canModerate = this.model.get('participantType') !== OCA.SpreedMe.app.OWNER &&       // can not moderate owners
-					this.model.get('userId') !== OC.getCurrentUser().uid &&                // can not moderate yourself
-					(OCA.SpreedMe.app.activeRoom.get('participantType') === OCA.SpreedMe.app.OWNER ||   // current user must be owner
-						OCA.SpreedMe.app.activeRoom.get('participantType') === OCA.SpreedMe.app.MODERATOR), // or moderator.
+					!isSelf && isModerator,
 					name = '';
 
 
@@ -123,8 +133,11 @@
 
 				return {
 					canModerate: canModerate,
+					canBePromoted: this.model.get('participantType') === OCA.SpreedMe.app.USER || this.model.get('participantType') === OCA.SpreedMe.app.GUEST,
+					canBeDemoted: this.model.get('participantType') === OCA.SpreedMe.app.MODERATOR || this.model.get('participantType') === OCA.SpreedMe.app.GUEST_MODERATOR,
 					name: name,
 					participantIsUser: this.model.get('participantType') === OCA.SpreedMe.app.USER,
+					participantIsGuestModerator: this.model.get('participantType') === OCA.SpreedMe.app.GUEST_MODERATOR,
 					participantIsModerator: this.model.get('participantType') === OCA.SpreedMe.app.MODERATOR,
 					participantIsOwner: this.model.get('participantType') === OCA.SpreedMe.app.OWNER
 				};
@@ -134,11 +147,14 @@
 				this.$el.find('.avatar').each(function() {
 					var $element = $(this);
 
-					if (model.get('participantType') !== OCA.SpreedMe.app.GUEST) {
-						$element.avatar(model.get('userId'), 32, undefined, false, undefined, model.get('displayName'));
-					} else {
+					if (model.get('participantType') === OCA.SpreedMe.app.GUEST_MODERATOR) {
+						$element.imageplaceholder('M', model.get('displayName'), 32);
+						$element.css('background-color', '#b9b9b9');
+					} else if (model.get('participantType') === OCA.SpreedMe.app.GUEST) {
 						$element.imageplaceholder('?', model.get('displayName'), 32);
 						$element.css('background-color', '#b9b9b9');
+					} else {
+						$element.avatar(model.get('userId'), 32, undefined, false, undefined, model.get('displayName'));
 					}
 				});
 
@@ -181,7 +197,8 @@
 				this.toggleMenuClass();
 			},
 			promoteToModerator: function() {
-				if (this.model.get('participantType') !== OCA.SpreedMe.app.USER) {
+				if (this.model.get('participantType') !== OCA.SpreedMe.app.USER &&
+					this.model.get('participantType') !== OCA.SpreedMe.app.GUEST) {
 					return;
 				}
 
@@ -189,17 +206,29 @@
 				this.ui.menuButton.addClass('hidden');
 				this.ui.menuButtonIconLoading.removeClass('hidden');
 
-				var participantId = this.model.get('userId'),
+				var data = {},
 					self = this;
 
+				if (this.model.get('userId')) {
+					data = {
+						participant: this.model.get('userId')
+					};
+				} else {
+					data = {
+						sessionId: this.model.get('sessionId')
+					};
+				}
+
 				$.ajax({
 					type: 'POST',
 					url: OC.linkToOCS('apps/spreed/api/v1/room', 2) + OCA.SpreedMe.app.activeRoom.get('token') + '/moderators',
-					data: {
-						participant: participantId
-					},
+					data: data,
 					success: function() {
-						self.model.set('participantType', OCA.SpreedMe.app.MODERATOR);
+						if (self.model.get('userId')) {
+							self.model.set('participantType', OCA.SpreedMe.app.MODERATOR);
+						} else {
+							self.model.set('participantType', OCA.SpreedMe.app.GUEST_MODERATOR);
+						}
 						// When an attribute that affects the order of a
 						// collection is set the collection has to be explicitly
 						// sorted again.
@@ -214,7 +243,8 @@
 				});
 			},
 			demoteFromModerator: function() {
-				if (this.model.get('participantType') !== OCA.SpreedMe.app.MODERATOR) {
+				if (this.model.get('participantType') !== OCA.SpreedMe.app.MODERATOR &&
+					this.model.get('participantType') !== OCA.SpreedMe.app.GUEST_MODERATOR) {
 					return;
 				}
 
@@ -222,17 +252,29 @@
 				this.ui.menuButton.addClass('hidden');
 				this.ui.menuButtonIconLoading.removeClass('hidden');
 
-				var participantId = this.model.get('userId'),
+				var data = {},
 					self = this;
 
+				if (this.model.get('userId')) {
+					data = {
+						participant: this.model.get('userId')
+					};
+				} else {
+					data = {
+						sessionId: this.model.get('sessionId')
+					};
+				}
+
 				$.ajax({
 					type: 'DELETE',
 					url: OC.linkToOCS('apps/spreed/api/v1/room', 2) + OCA.SpreedMe.app.activeRoom.get('token') + '/moderators',
-					data: {
-						participant: participantId
-					},
+					data:data,
 					success: function() {
-						self.model.set('participantType', OCA.SpreedMe.app.USER);
+						if (self.model.get('userId')) {
+							self.model.set('participantType', OCA.SpreedMe.app.USER);
+						} else {
+							self.model.set('participantType', OCA.SpreedMe.app.GUEST);
+						}
 						// When an attribute that affects the order of a
 						// collection is set the collection has to be explicitly
 						// sorted again.
@@ -259,7 +301,8 @@
 					participantId = this.model.get('userId'),
 					endpoint = '/participants';
 
-				if (this.model.get('participantType') === OCA.SpreedMe.app.GUEST) {
+				if (this.model.get('participantType') === OCA.SpreedMe.app.GUEST ||
+						this.model.get('participantType') === OCA.SpreedMe.app.GUEST_MODERATOR) {
 					participantId = this.model.get('sessionId');
 					endpoint += '/guests';
 				}
diff --git a/lib/AppInfo/Application.php b/lib/AppInfo/Application.php
index 0dff92d34e4..877c9472a7d 100644
--- a/lib/AppInfo/Application.php
+++ b/lib/AppInfo/Application.php
@@ -162,6 +162,15 @@ protected function registerSignalingBackendHooks(EventDispatcherInterface $dispa
 			// so they can update the room properties.
 			$notifier->roomModified($room);
 		});
+		$dispatcher->addListener(Room::class . '::postSetParticipantTypeBySession', function(GenericEvent $event) {
+			/** @var BackendNotifier $notifier */
+			$notifier = $this->getBackendNotifier();
+
+			$room = $event->getSubject();
+			// The type of a participant has changed, notify all participants
+			// so they can update the room properties.
+			$notifier->roomModified($room);
+		});
 		$dispatcher->addListener(Room::class . '::postDeleteRoom', function(GenericEvent $event) {
 			/** @var BackendNotifier $notifier */
 			$notifier = $this->getBackendNotifier();
diff --git a/lib/Chat/MessageParser.php b/lib/Chat/MessageParser.php
index 2a7bcd0454f..27c89b9f25a 100644
--- a/lib/Chat/MessageParser.php
+++ b/lib/Chat/MessageParser.php
@@ -23,6 +23,7 @@
 
 namespace OCA\Spreed\Chat;
 
+use OCA\Spreed\Room;
 use OCP\Comments\IComment;
 use OCP\IL10N;
 use OCP\IUser;
@@ -41,8 +42,9 @@ public function __construct(EventDispatcherInterface $dispatcher) {
 		$this->dispatcher = $dispatcher;
 	}
 
-	public function parseMessage(IComment $chatMessage, IL10N $l, IUser $user = null): array {
+	public function parseMessage(Room $room, IComment $chatMessage, IL10N $l, IUser $user = null): array {
 		$event = new GenericEvent($chatMessage, [
+			'room' => $room,
 			'user' => $user,
 			'l10n' => $l,
 		]);
diff --git a/lib/Chat/Parser/SystemMessage.php b/lib/Chat/Parser/SystemMessage.php
index e5c3882f7eb..fdd428b28c0 100644
--- a/lib/Chat/Parser/SystemMessage.php
+++ b/lib/Chat/Parser/SystemMessage.php
@@ -54,6 +54,8 @@ class SystemMessage {
 
 	/** @var null|IUser */
 	protected $recipient;
+	/** @var null|string */
+	protected $sessionId;
 	/** @var string[] */
 	protected $displayNames = [];
 	/** @var string[] */
@@ -79,6 +81,13 @@ public function __construct(IUserManager $userManager,
 	public function setUserInfo(IL10N $l, IUser $user = null) {
 		$this->l = $l;
 		$this->recipient = $user;
+		$this->sessionId = null;
+	}
+
+	public function setGuestInfo(IL10N $l, string $sessionId = null) {
+		$this->l = $l;
+		$this->recipient = null;
+		$this->sessionId = $sessionId;
 	}
 
 	/**
@@ -95,7 +104,8 @@ public function parseMessage(IComment $comment): array {
 		$message = $data['message'];
 		$parameters = $data['parameters'];
 		$parsedParameters = ['actor' => $this->getActor($comment)];
-		$currentUserIsActor = $this->recipient instanceof IUser && $this->recipient->getUID() === $parsedParameters['actor']['id'];
+		$currentUserIsActor = ($this->recipient instanceof IUser && $parsedParameters['actor']['type'] === 'user' && $this->recipient->getUID() === $parsedParameters['actor']['id']) ||
+			($this->sessionId !== null && $parsedParameters['actor']['type'] === 'guest' && $this->sessionId === $parsedParameters['actor']['id']);
 
 		if ($message === 'conversation_created') {
 			$parsedMessage = $this->l->t('{actor} created the conversation');
@@ -180,6 +190,22 @@ public function parseMessage(IComment $comment): array {
 			} else if ($this->recipient instanceof IUser && $this->recipient->getUID() === $parsedParameters['user']['id']) {
 				$parsedMessage = $this->l->t('{actor} demoted you from moderator');
 			}
+		} else if ($message === 'guest_moderator_promoted') {
+			$parsedParameters['user'] = $this->getGuest($parameters['session']);
+			$parsedMessage = $this->l->t('{actor} promoted {user} to moderator');
+			if ($currentUserIsActor) {
+				$parsedMessage = $this->l->t('You promoted {user} to moderator');
+			} else if ($this->sessionId !== null && $this->sessionId === $parsedParameters['user']['id']) {
+				$parsedMessage = $this->l->t('{actor} promoted you to moderator');
+			}
+		} else if ($message === 'guest_moderator_demoted') {
+			$parsedParameters['user'] = $this->getGuest($parameters['session']);
+			$parsedMessage = $this->l->t('{actor} demoted {user} from moderator');
+			if ($currentUserIsActor) {
+				$parsedMessage = $this->l->t('You demoted {user} from moderator');
+			} else if ($this->sessionId !== null && $this->sessionId === $parsedParameters['user']['id']) {
+				$parsedMessage = $this->l->t('{actor} demoted you from moderator');
+			}
 		} else if ($message === 'file_shared') {
 			try {
 				$parsedParameters['file'] = $this->getFileFromShare($parameters['share']);
diff --git a/lib/Chat/SystemMessage/Listener.php b/lib/Chat/SystemMessage/Listener.php
index 606f982a573..65da003545a 100644
--- a/lib/Chat/SystemMessage/Listener.php
+++ b/lib/Chat/SystemMessage/Listener.php
@@ -139,6 +139,18 @@ public function register() {
 				$this->sendSystemMessage($room, 'moderator_demoted', ['user' => $event->getArgument('user')]);
 			}
 		});
+		$this->dispatcher->addListener(Room::class . '::postSetParticipantTypeBySession', function(GenericEvent $event) {
+			/** @var Room $room */
+			$room = $event->getSubject();
+			/** @var Participant $participant */
+			$participant = $event->getArgument('participant');
+
+			if ($event->getArgument('newType') === Participant::GUEST_MODERATOR) {
+				$this->sendSystemMessage($room, 'guest_moderator_promoted', ['session' => sha1($participant->getSessionId())]);
+			} else if ($event->getArgument('newType') === Participant::GUEST) {
+				$this->sendSystemMessage($room, 'guest_moderator_demoted', ['session' => sha1($participant->getSessionId())]);
+			}
+		});
 		$listener = function(GenericEvent $event) {
 			/** @var IShare $share */
 			$share = $event->getSubject();
@@ -152,6 +164,7 @@ public function register() {
 		};
 		$this->dispatcher->addListener('OCP\Share::postShare', $listener);
 		$this->dispatcher->addListener(RoomShareProvider::class . '::' . 'share_file_again', $listener);
+
 		$this->dispatcher->addListener(MessageParser::class . '::parseMessage', function(GenericEvent $event) {
 			/** @var IComment $chatMessage */
 			$chatMessage = $event->getSubject();
@@ -162,7 +175,17 @@ public function register() {
 
 			/** @var SystemMessage $parser */
 			$parser = \OC::$server->query(SystemMessage::class);
-			$parser->setUserInfo($event->getArgument('l10n'), $event->getArgument('user'));
+
+			$user = $event->getArgument('user');
+			if ($user instanceof IUser) {
+				$parser->setUserInfo($event->getArgument('l10n'), $event->getArgument('user'));
+			} else {
+				/** @var Room $room */
+				$room = $event->getArgument('room');
+				/** @var TalkSession $talkSession */
+				$talkSession = \OC::$server->query(TalkSession::class);
+				$parser->setGuestInfo($event->getArgument('l10n'), sha1($talkSession->getSessionForRoom($room->getToken())));
+			}
 
 			try {
 				list($message, $parameters) = $parser->parseMessage($chatMessage);
diff --git a/lib/Controller/ChatController.php b/lib/Controller/ChatController.php
index a1ca6b55d06..fd6cacfbfb0 100644
--- a/lib/Controller/ChatController.php
+++ b/lib/Controller/ChatController.php
@@ -280,7 +280,7 @@ public function receiveMessages($token, $lookIntoFuture, $limit = 100, $lastKnow
 		}
 
 		$guestNames = !empty($guestSessions) ? $this->guestManager->getNamesBySessionHashes($guestSessions) : [];
-		$response = new DataResponse(array_map(function (IComment $comment) use ($token, $guestNames, $currentUser) {
+		$response = new DataResponse(array_map(function (IComment $comment) use ($room, $token, $guestNames, $currentUser) {
 			$displayName = '';
 			if ($comment->getActorType() === 'users') {
 				$user = $this->userManager->get($comment->getActorId());
@@ -289,7 +289,7 @@ public function receiveMessages($token, $lookIntoFuture, $limit = 100, $lastKnow
 				$displayName = $guestNames[$comment->getActorId()];
 			}
 
-			list($message, $messageParameters) = $this->messageParser->parseMessage($comment, $this->l, $currentUser);
+			list($message, $messageParameters) = $this->messageParser->parseMessage($room, $comment, $this->l, $currentUser);
 
 			return [
 				'id' => (int) $comment->getId(),
diff --git a/lib/Controller/RoomController.php b/lib/Controller/RoomController.php
index 5adce6d001f..009c64ac153 100644
--- a/lib/Controller/RoomController.php
+++ b/lib/Controller/RoomController.php
@@ -276,7 +276,7 @@ protected function formatRoom(Room $room, Participant $participant = null): arra
 
 		$lastMessage = $room->getLastMessage();
 		if ($lastMessage instanceof IComment) {
-			$lastMessage = $this->formatLastMessage($lastMessage, $currentUser);
+			$lastMessage = $this->formatLastMessage($room, $lastMessage, $currentUser);
 		} else {
 			$lastMessage = [];
 		}
@@ -361,12 +361,13 @@ protected function formatRoom(Room $room, Participant $participant = null): arra
 	}
 
 	/**
+	 * @param Room $room
 	 * @param IComment $lastMessage
 	 * @param IUser $currentUser
 	 * @return array
 	 */
-	protected function formatLastMessage(IComment $lastMessage, IUser $currentUser = null): array {
-		list($message, $messageParameters) = $this->messageParser->parseMessage($lastMessage, $this->l10n, $currentUser);
+	protected function formatLastMessage(Room $room, IComment $lastMessage, IUser $currentUser = null): array {
+		list($message, $messageParameters) = $this->messageParser->parseMessage($room, $lastMessage, $this->l10n, $currentUser);
 
 		$displayName = '';
 
@@ -589,7 +590,7 @@ public function removeFromFavorites(string $token): DataResponse {
 
 
 	/**
-	 * @NoAdminRequired
+	 * @PublicPage
 	 *
 	 * @param string $token
 	 * @param string $roomName
@@ -598,14 +599,19 @@ public function removeFromFavorites(string $token): DataResponse {
 	public function renameRoom(string $token, string $roomName): DataResponse {
 		try {
 			$room = $this->manager->getRoomForParticipantByToken($token, $this->userId);
-			$participant = $room->getParticipant($this->userId);
+			if ($this->userId !== null) {
+				$participant = $room->getParticipant($this->userId);
+			} else {
+				$sessionId = $this->session->getSessionForRoom($token);
+				$participant = $room->getParticipantBySession($sessionId);
+			}
 		} catch (RoomNotFoundException $e) {
 			return new DataResponse([], Http::STATUS_NOT_FOUND);
 		} catch (ParticipantNotFoundException $e) {
 			return new DataResponse([], Http::STATUS_NOT_FOUND);
 		}
 
-		if (!\in_array($participant->getParticipantType(), [Participant::OWNER, Participant::MODERATOR], true)) {
+		if (!$participant->hasModeratorPermissions()) {
 			return new DataResponse([], Http::STATUS_FORBIDDEN);
 		}
 
@@ -621,7 +627,7 @@ public function renameRoom(string $token, string $roomName): DataResponse {
 	}
 
 	/**
-	 * @NoAdminRequired
+	 * @PublicPage
 	 *
 	 * @param string $token
 	 * @return DataResponse
@@ -629,14 +635,19 @@ public function renameRoom(string $token, string $roomName): DataResponse {
 	public function deleteRoom(string $token): DataResponse {
 		try {
 			$room = $this->manager->getRoomForParticipantByToken($token, $this->userId);
-			$participant = $room->getParticipant($this->userId);
+			if ($this->userId !== null) {
+				$participant = $room->getParticipant($this->userId);
+			} else {
+				$sessionId = $this->session->getSessionForRoom($token);
+				$participant = $room->getParticipantBySession($sessionId);
+			}
 		} catch (RoomNotFoundException $e) {
 			return new DataResponse([], Http::STATUS_NOT_FOUND);
 		} catch (ParticipantNotFoundException $e) {
 			return new DataResponse([], Http::STATUS_NOT_FOUND);
 		}
 
-		if (!\in_array($participant->getParticipantType(), [Participant::OWNER, Participant::MODERATOR], true)) {
+		if (!$participant->hasModeratorPermissions()) {
 			return new DataResponse([], Http::STATUS_FORBIDDEN);
 		}
 
@@ -646,7 +657,7 @@ public function deleteRoom(string $token): DataResponse {
 	}
 
 	/**
-	 * @NoAdminRequired
+	 * @PublicPage
 	 *
 	 * @param string $token
 	 * @return DataResponse
@@ -654,8 +665,20 @@ public function deleteRoom(string $token): DataResponse {
 	public function getParticipants(string $token): DataResponse {
 		try {
 			$room = $this->manager->getRoomForParticipantByToken($token, $this->userId);
+			if ($this->userId !== null) {
+				$participant = $room->getParticipant($this->userId);
+			} else {
+				$sessionId = $this->session->getSessionForRoom($token);
+				$participant = $room->getParticipantBySession($sessionId);
+			}
 		} catch (RoomNotFoundException $e) {
 			return new DataResponse([], Http::STATUS_NOT_FOUND);
+		} catch (ParticipantNotFoundException $e) {
+			return new DataResponse([], Http::STATUS_NOT_FOUND);
+		}
+
+		if ($participant->getParticipantType() === Participant::GUEST) {
+			return new DataResponse([], Http::STATUS_FORBIDDEN);
 		}
 
 		$participants = $room->getParticipants();
@@ -682,7 +705,6 @@ public function getParticipants(string $token): DataResponse {
 		foreach ($participants['guests'] as $participant) {
 			$sessionHash = sha1($participant['sessionId']);
 			$results[] = array_merge($participant, [
-				'participantType' => Participant::GUEST,
 				'userId' => '',
 				'displayName' => $guestNames[$sessionHash] ?? '',
 			]);
@@ -708,7 +730,7 @@ public function addParticipantToRoom(string $token, string $newParticipant): Dat
 			return new DataResponse([], Http::STATUS_NOT_FOUND);
 		}
 
-		if (!\in_array($participant->getParticipantType(), [Participant::OWNER, Participant::MODERATOR], true)) {
+		if (!$participant->hasModeratorPermissions(false)) {
 			return new DataResponse([], Http::STATUS_FORBIDDEN);
 		}
 
@@ -743,7 +765,7 @@ public function addParticipantToRoom(string $token, string $newParticipant): Dat
 	}
 
 	/**
-	 * @NoAdminRequired
+	 * @PublicPage
 	 *
 	 * @param string $token
 	 * @param string $newParticipant
@@ -759,7 +781,7 @@ public function inviteEmailToRoom($token, $newParticipant): DataResponse {
 			return new DataResponse([], Http::STATUS_NOT_FOUND);
 		}
 
-		if (!\in_array($participant->getParticipantType(), [Participant::OWNER, Participant::MODERATOR], true)) {
+		if (!$participant->hasModeratorPermissions(false)) {
 			return new DataResponse([], Http::STATUS_FORBIDDEN);
 		}
 
@@ -783,7 +805,7 @@ public function inviteEmailToRoom($token, $newParticipant): DataResponse {
 	}
 
 	/**
-	 * @NoAdminRequired
+	 * @PublicPage
 	 *
 	 * @param string $token
 	 * @param string $participant
@@ -792,14 +814,19 @@ public function inviteEmailToRoom($token, $newParticipant): DataResponse {
 	public function removeParticipantFromRoom(string $token, string $participant): DataResponse {
 		try {
 			$room = $this->manager->getRoomForParticipantByToken($token, $this->userId);
-			$currentParticipant = $room->getParticipant($this->userId);
+			if ($this->userId !== null) {
+				$currentParticipant = $room->getParticipant($this->userId);
+			} else {
+				$sessionId = $this->session->getSessionForRoom($token);
+				$currentParticipant = $room->getParticipantBySession($sessionId);
+			}
 		} catch (RoomNotFoundException $e) {
 			return new DataResponse([], Http::STATUS_NOT_FOUND);
 		} catch (ParticipantNotFoundException $e) {
 			return new DataResponse([], Http::STATUS_NOT_FOUND);
 		}
 
-		if (!\in_array($currentParticipant->getParticipantType(), [Participant::OWNER, Participant::MODERATOR], true)) {
+		if (!$currentParticipant->hasModeratorPermissions()) {
 			return new DataResponse([], Http::STATUS_FORBIDDEN);
 		}
 
@@ -858,7 +885,7 @@ public function removeSelfFromRoom(string $token): DataResponse {
 	}
 
 	/**
-	 * @NoAdminRequired
+	 * @PublicPage
 	 *
 	 * @param string $token
 	 * @param string $participant
@@ -867,14 +894,19 @@ public function removeSelfFromRoom(string $token): DataResponse {
 	public function removeGuestFromRoom(string $token, string $participant): DataResponse {
 		try {
 			$room = $this->manager->getRoomForParticipantByToken($token, $this->userId);
-			$currentParticipant = $room->getParticipant($this->userId);
+			if ($this->userId !== null) {
+				$currentParticipant = $room->getParticipant($this->userId);
+			} else {
+				$sessionId = $this->session->getSessionForRoom($token);
+				$currentParticipant = $room->getParticipantBySession($sessionId);
+			}
 		} catch (RoomNotFoundException $e) {
 			return new DataResponse([], Http::STATUS_NOT_FOUND);
 		} catch (ParticipantNotFoundException $e) {
 			return new DataResponse([], Http::STATUS_NOT_FOUND);
 		}
 
-		if (!\in_array($currentParticipant->getParticipantType(), [Participant::OWNER, Participant::MODERATOR], true)) {
+		if (!$currentParticipant->hasModeratorPermissions()) {
 			return new DataResponse([], Http::STATUS_FORBIDDEN);
 		}
 
@@ -884,7 +916,11 @@ public function removeGuestFromRoom(string $token, string $participant): DataRes
 			return new DataResponse([], Http::STATUS_NOT_FOUND);
 		}
 
-		if ($targetParticipant->getParticipantType() !== Participant::GUEST) {
+		if (!$targetParticipant->isGuest()) {
+			return new DataResponse([], Http::STATUS_PRECONDITION_FAILED);
+		}
+
+		if ($targetParticipant->getSessionId() === $currentParticipant->getSessionId()) {
 			return new DataResponse([], Http::STATUS_FORBIDDEN);
 		}
 
@@ -908,7 +944,7 @@ public function makePublic(string $token): DataResponse {
 			return new DataResponse([], Http::STATUS_NOT_FOUND);
 		}
 
-		if (!\in_array($participant->getParticipantType(), [Participant::OWNER, Participant::MODERATOR], true)) {
+		if (!$participant->hasModeratorPermissions(false)) {
 			return new DataResponse([], Http::STATUS_FORBIDDEN);
 		}
 
@@ -935,7 +971,7 @@ public function makePrivate(string $token): DataResponse {
 			return new DataResponse([], Http::STATUS_NOT_FOUND);
 		}
 
-		if (!\in_array($participant->getParticipantType(), [Participant::OWNER, Participant::MODERATOR], true)) {
+		if (!$participant->hasModeratorPermissions(false)) {
 			return new DataResponse([], Http::STATUS_FORBIDDEN);
 		}
 
@@ -947,7 +983,7 @@ public function makePrivate(string $token): DataResponse {
 	}
 
 	/**
-	 * @NoAdminRequired
+	 * @PublicPage
 	 *
 	 * @param string $token
 	 * @param string $password
@@ -956,14 +992,19 @@ public function makePrivate(string $token): DataResponse {
 	public function setPassword(string $token, string $password): DataResponse {
 		try {
 			$room = $this->manager->getRoomForParticipantByToken($token, $this->userId);
-			$participant = $room->getParticipant($this->userId);
+			if ($this->userId !== null) {
+				$participant = $room->getParticipant($this->userId);
+			} else {
+				$sessionId = $this->session->getSessionForRoom($token);
+				$participant = $room->getParticipantBySession($sessionId);
+			}
 		} catch (RoomNotFoundException $e) {
 			return new DataResponse([], Http::STATUS_NOT_FOUND);
 		} catch (ParticipantNotFoundException $e) {
 			return new DataResponse([], Http::STATUS_NOT_FOUND);
 		}
 
-		if (!\in_array($participant->getParticipantType(), [Participant::OWNER, Participant::MODERATOR], true)) {
+		if (!$participant->hasModeratorPermissions()) {
 			return new DataResponse([], Http::STATUS_FORBIDDEN);
 		}
 
@@ -1038,26 +1079,40 @@ public function leaveRoom(string $token): DataResponse {
 	}
 
 	/**
-	 * @NoAdminRequired
+	 * @PublicPage
 	 *
 	 * @param string $token
-	 * @param string $participant
+	 * @param string|null $participant
+	 * @param string|null $sessionId
 	 * @return DataResponse
 	 */
-	public function promoteModerator(string $token, string $participant): DataResponse {
+	public function promoteModerator(string $token, $participant, $sessionId): DataResponse {
 		try {
 			$room = $this->manager->getRoomForParticipantByToken($token, $this->userId);
-			$currentParticipant = $room->getParticipant($this->userId);
+			if ($this->userId !== null) {
+				$currentParticipant = $room->getParticipant($this->userId);
+			} else {
+				$currentSessionId = $this->session->getSessionForRoom($token);
+				$currentParticipant = $room->getParticipantBySession($currentSessionId);
+			}
 		} catch (RoomNotFoundException $e) {
 			return new DataResponse([], Http::STATUS_NOT_FOUND);
 		} catch (ParticipantNotFoundException $e) {
 			return new DataResponse([], Http::STATUS_NOT_FOUND);
 		}
 
-		if (!\in_array($currentParticipant->getParticipantType(), [Participant::OWNER, Participant::MODERATOR], true)) {
+		if (!$currentParticipant->hasModeratorPermissions()) {
 			return new DataResponse([], Http::STATUS_FORBIDDEN);
 		}
 
+		if ($participant !== null) {
+			return $this->promoteUserToModerator($room, $participant);
+		}
+
+		return $this->promoteGuestToModerator($room, $sessionId);
+	}
+
+	protected function promoteUserToModerator(Room $room, string $participant): DataResponse {
 		try {
 			$targetParticipant = $room->getParticipant($participant);
 		} catch (ParticipantNotFoundException $e) {
@@ -1073,28 +1128,58 @@ public function promoteModerator(string $token, string $participant): DataRespon
 		return new DataResponse();
 	}
 
+	protected function promoteGuestToModerator(Room $room, string $sessionId): DataResponse {
+		try {
+			$targetParticipant = $room->getParticipantBySession($sessionId);
+		} catch (ParticipantNotFoundException $e) {
+			return new DataResponse([], Http::STATUS_NOT_FOUND);
+		}
+
+		if ($targetParticipant->getParticipantType() !== Participant::GUEST) {
+			return new DataResponse([], Http::STATUS_PRECONDITION_FAILED);
+		}
+
+		$room->setParticipantTypeBySession($targetParticipant, Participant::GUEST_MODERATOR);
+
+		return new DataResponse();
+	}
+
 	/**
-	 * @NoAdminRequired
+	 * @PublicPage
 	 *
 	 * @param string $token
-	 * @param string $participant
+	 * @param string|null $participant
+	 * @param string|null $sessionId
 	 * @return DataResponse
 	 */
-	public function demoteModerator(string $token, string $participant): DataResponse {
+	public function demoteModerator(string $token, $participant, $sessionId): DataResponse {
 		try {
 			$room = $this->manager->getRoomForParticipantByToken($token, $this->userId);
-			$currentParticipant = $room->getParticipant($this->userId);
+			if ($this->userId !== null) {
+				$currentParticipant = $room->getParticipant($this->userId);
+			} else {
+				$currentSessionId = $this->session->getSessionForRoom($token);
+				$currentParticipant = $room->getParticipantBySession($currentSessionId);
+			}
 		} catch (RoomNotFoundException $e) {
 			return new DataResponse([], Http::STATUS_NOT_FOUND);
 		} catch (ParticipantNotFoundException $e) {
 			return new DataResponse([], Http::STATUS_NOT_FOUND);
 		}
 
-		if ($this->userId === $participant) {
+		if (!$currentParticipant->hasModeratorPermissions()) {
 			return new DataResponse([], Http::STATUS_FORBIDDEN);
 		}
 
-		if (!\in_array($currentParticipant->getParticipantType(), [Participant::OWNER, Participant::MODERATOR], true)) {
+		if ($participant !== null) {
+			return $this->demoteUserFromModerator($room, $participant);
+		}
+
+		return $this->demoteGuestFromModerator($room, $sessionId);
+	}
+
+	protected function demoteUserFromModerator(Room $room, string $participant): DataResponse {
+		if ($this->userId === $participant) {
 			return new DataResponse([], Http::STATUS_FORBIDDEN);
 		}
 
@@ -1112,4 +1197,24 @@ public function demoteModerator(string $token, string $participant): DataRespons
 
 		return new DataResponse();
 	}
+
+	protected function demoteGuestFromModerator(Room $room, string $sessionId): DataResponse {
+		if ($this->session->getSessionForRoom($room->getToken()) === $sessionId) {
+			return new DataResponse([], Http::STATUS_FORBIDDEN);
+		}
+
+		try {
+			$targetParticipant = $room->getParticipantBySession($sessionId);
+		} catch (ParticipantNotFoundException $e) {
+			return new DataResponse([], Http::STATUS_NOT_FOUND);
+		}
+
+		if ($targetParticipant->getParticipantType() !== Participant::GUEST_MODERATOR) {
+			return new DataResponse([], Http::STATUS_PRECONDITION_FAILED);
+		}
+
+		$room->setParticipantTypeBySession($targetParticipant, Participant::GUEST);
+
+		return new DataResponse();
+	}
 }
diff --git a/lib/Notification/Notifier.php b/lib/Notification/Notifier.php
index d9cd378ff9c..35a07aa257f 100644
--- a/lib/Notification/Notifier.php
+++ b/lib/Notification/Notifier.php
@@ -174,7 +174,7 @@ protected function parseChatMessage(INotification $notification, Room $room, IL1
 		}
 
 		$recipient = $this->userManager->get($notification->getUser());
-		list($richMessage, $richMessageParameters) = $this->messageParser->parseMessage($comment, $l, $recipient);
+		list($richMessage, $richMessageParameters) = $this->messageParser->parseMessage($room, $comment, $l, $recipient);
 
 		$placeholders = $replacements = [];
 		foreach ($richMessageParameters as $placeholder => $parameter) {
diff --git a/lib/Participant.php b/lib/Participant.php
index b786d40099f..8b424cb44d0 100644
--- a/lib/Participant.php
+++ b/lib/Participant.php
@@ -34,6 +34,7 @@ class Participant {
 	const USER = 3;
 	const GUEST = 4;
 	const USER_SELF_JOINED = 5;
+	const GUEST_MODERATOR = 6;
 
 	const FLAG_DISCONNECTED = 0;
 	const FLAG_IN_CALL = 1;
@@ -79,6 +80,18 @@ public function getParticipantType(): int {
 		return $this->participantType;
 	}
 
+	public function isGuest(): bool {
+		return \in_array($this->participantType, [self::GUEST, self::GUEST_MODERATOR], true);
+	}
+
+	public function hasModeratorPermissions(bool $guestModeratorAllowed = true): bool {
+		if (!$guestModeratorAllowed) {
+			return \in_array($this->participantType, [self::OWNER, self::MODERATOR], true);
+		}
+
+		return \in_array($this->participantType, [self::OWNER, self::MODERATOR, self::GUEST_MODERATOR], true);
+	}
+
 	public function getLastPing(): int {
 		return $this->lastPing;
 	}
diff --git a/lib/Room.php b/lib/Room.php
index 25afadfe4f7..8dba7f25835 100644
--- a/lib/Room.php
+++ b/lib/Room.php
@@ -526,6 +526,29 @@ public function setParticipantType($participant, $participantType) {
 		]));
 	}
 
+	/**
+	 * @param Participant $participant
+	 * @param int $participantType
+	 */
+	public function setParticipantTypeBySession(Participant $participant, int $participantType) {
+		$this->dispatcher->dispatch(self::class . '::preSetParticipantTypeBySession', new GenericEvent($this, [
+			'participant' => $participant,
+			'newType' => $participantType,
+		]));
+
+		$query = $this->db->getQueryBuilder();
+		$query->update('talk_participants')
+			->set('participant_type', $query->createNamedParameter($participantType, IQueryBuilder::PARAM_INT))
+			->where($query->expr()->eq('room_id', $query->createNamedParameter($this->getId(), IQueryBuilder::PARAM_INT)))
+			->andWhere($query->expr()->eq('session_id', $query->createNamedParameter($participant->getSessionId())));
+		$query->execute();
+
+		$this->dispatcher->dispatch(self::class . '::postSetParticipantTypeBySession', new GenericEvent($this, [
+			'participant' => $participant,
+			'newType' => $participantType,
+		]));
+	}
+
 	/**
 	 * @param IUser $user
 	 */
@@ -791,6 +814,7 @@ public function getParticipants($lastPing = 0) {
 				$guests[] = [
 					'inCall' => (int) $row['in_call'],
 					'lastPing' => (int) $row['last_ping'],
+					'participantType' => (int) $row['participant_type'],
 					'sessionId' => $row['session_id'],
 				];
 			}
diff --git a/templates/index-public.php b/templates/index-public.php
index 573809bd083..562200b03c5 100644
--- a/templates/index-public.php
+++ b/templates/index-public.php
@@ -22,9 +22,13 @@
 		'models/localstoragemodel',
 		'models/room',
 		'models/roomcollection',
+		'models/participant',
+		'models/participantcollection',
 		'views/callinfoview',
 		'views/chatview',
 		'views/editabletextlabel',
+		'views/participantlistview',
+		'views/participantview',
 		'views/roomlistview',
 		'views/sidebarview',
 		'views/tabview',
diff --git a/tests/php/Chat/Parser/SystemMessageTest.php b/tests/php/Chat/Parser/SystemMessageTest.php
index 10bd954aefc..846fb86c2da 100644
--- a/tests/php/Chat/Parser/SystemMessageTest.php
+++ b/tests/php/Chat/Parser/SystemMessageTest.php
@@ -115,63 +115,63 @@ public function dataParseMessage(): array {
 		return [
 			['conversation_created', [], null, [
 				'{actor} created the conversation',
-				['actor' => ['id' => 'actor']],
+				['actor' => ['id' => 'actor', 'type' => 'user']],
 			]],
 			['conversation_created', [], 'recipient', [
 				'{actor} created the conversation',
-				['actor' => ['id' => 'actor']],
+				['actor' => ['id' => 'actor', 'type' => 'user']],
 			]],
 			['conversation_created', [], 'actor', [
 				'You created the conversation',
-				['actor' => ['id' => 'actor']],
+				['actor' => ['id' => 'actor', 'type' => 'user']],
 			]],
 			['conversation_renamed', ['oldName' => 'old', 'newName' => 'new'], null, [
 				'{actor} renamed the conversation from "old" to "new"',
-				['actor' => ['id' => 'actor']],
+				['actor' => ['id' => 'actor', 'type' => 'user']],
 			]],
 			['conversation_renamed', ['oldName' => 'old', 'newName' => 'new'], 'recipient', [
 				'{actor} renamed the conversation from "old" to "new"',
-				['actor' => ['id' => 'actor']],
+				['actor' => ['id' => 'actor', 'type' => 'user']],
 			]],
 			['conversation_renamed', ['oldName' => 'old', 'newName' => 'new'], 'actor', [
 				'You renamed the conversation from "old" to "new"',
-				['actor' => ['id' => 'actor']],
+				['actor' => ['id' => 'actor', 'type' => 'user']],
 			]],
 			['call_started', [], null, [
 				'{actor} started a call',
-				['actor' => ['id' => 'actor']],
+				['actor' => ['id' => 'actor', 'type' => 'user']],
 			]],
 			['call_started', [], 'recipient', [
 				'{actor} started a call',
-				['actor' => ['id' => 'actor']],
+				['actor' => ['id' => 'actor', 'type' => 'user']],
 			]],
 			['call_started', [], 'actor', [
 				'You started a call',
-				['actor' => ['id' => 'actor']],
+				['actor' => ['id' => 'actor', 'type' => 'user']],
 			]],
 			['call_joined', [], null, [
 				'{actor} joined the call',
-				['actor' => ['id' => 'actor']],
+				['actor' => ['id' => 'actor', 'type' => 'user']],
 			]],
 			['call_joined', [], 'recipient', [
 				'{actor} joined the call',
-				['actor' => ['id' => 'actor']],
+				['actor' => ['id' => 'actor', 'type' => 'user']],
 			]],
 			['call_joined', [], 'actor', [
 				'You joined the call',
-				['actor' => ['id' => 'actor']],
+				['actor' => ['id' => 'actor', 'type' => 'user']],
 			]],
 			['call_left', [], null, [
 				'{actor} left the call',
-				['actor' => ['id' => 'actor']],
+				['actor' => ['id' => 'actor', 'type' => 'user']],
 			]],
 			['call_left', [], 'recipient', [
 				'{actor} left the call',
-				['actor' => ['id' => 'actor']],
+				['actor' => ['id' => 'actor', 'type' => 'user']],
 			]],
 			['call_left', [], 'actor', [
 				'You left the call',
-				['actor' => ['id' => 'actor']],
+				['actor' => ['id' => 'actor', 'type' => 'user']],
 			]],
 			['call_ended', [], null, [
 				'tested by testParsecall', []
@@ -184,143 +184,183 @@ public function dataParseMessage(): array {
 			]],
 			['guests_allowed', [], null, [
 				'{actor} allowed guests',
-				['actor' => ['id' => 'actor']],
+				['actor' => ['id' => 'actor', 'type' => 'user']],
 			]],
 			['guests_allowed', [], 'recipient', [
 				'{actor} allowed guests',
-				['actor' => ['id' => 'actor']],
+				['actor' => ['id' => 'actor', 'type' => 'user']],
 			]],
 			['guests_allowed', [], 'actor', [
 				'You allowed guests',
-				['actor' => ['id' => 'actor']],
+				['actor' => ['id' => 'actor', 'type' => 'user']],
 			]],
 			['guests_disallowed', [], null, [
 				'{actor} disallowed guests',
-				['actor' => ['id' => 'actor']],
+				['actor' => ['id' => 'actor', 'type' => 'user']],
 			]],
 			['guests_disallowed', [], 'recipient', [
 				'{actor} disallowed guests',
-				['actor' => ['id' => 'actor']],
+				['actor' => ['id' => 'actor', 'type' => 'user']],
 			]],
 			['guests_disallowed', [], 'actor', [
 				'You disallowed guests',
-				['actor' => ['id' => 'actor']],
+				['actor' => ['id' => 'actor', 'type' => 'user']],
 			]],
 			['password_set', [], null, [
 				'{actor} set a password',
-				['actor' => ['id' => 'actor']],
+				['actor' => ['id' => 'actor', 'type' => 'user']],
 			]],
 			['password_set', [], 'recipient', [
 				'{actor} set a password',
-				['actor' => ['id' => 'actor']],
+				['actor' => ['id' => 'actor', 'type' => 'user']],
 			]],
 			['password_set', [], 'actor', [
 				'You set a password',
-				['actor' => ['id' => 'actor']],
+				['actor' => ['id' => 'actor', 'type' => 'user']],
 			]],
 			['password_removed', [], null, [
 				'{actor} removed the password',
-				['actor' => ['id' => 'actor']],
+				['actor' => ['id' => 'actor', 'type' => 'user']],
 			]],
 			['password_removed', [], 'recipient', [
 				'{actor} removed the password',
-				['actor' => ['id' => 'actor']],
+				['actor' => ['id' => 'actor', 'type' => 'user']],
 			]],
 			['password_removed', [], 'actor', [
 				'You removed the password',
-				['actor' => ['id' => 'actor']],
+				['actor' => ['id' => 'actor', 'type' => 'user']],
 			]],
 			['user_added', ['user' => 'user'], null, [
 				'{actor} added {user}',
-				['actor' => ['id' => 'actor'], 'user' => ['id' => 'user']],
+				['actor' => ['id' => 'actor', 'type' => 'user'], 'user' => ['id' => 'user', 'type' => 'user']],
 			]],
 			['user_added', ['user' => 'user'], 'recipient', [
 				'{actor} added {user}',
-				['actor' => ['id' => 'actor'], 'user' => ['id' => 'user']],
+				['actor' => ['id' => 'actor', 'type' => 'user'], 'user' => ['id' => 'user', 'type' => 'user']],
 			]],
 			['user_added', ['user' => 'user'], 'user', [
 				'{actor} added you',
-				['actor' => ['id' => 'actor'], 'user' => ['id' => 'user']],
+				['actor' => ['id' => 'actor', 'type' => 'user'], 'user' => ['id' => 'user', 'type' => 'user']],
 			]],
 			['user_added', ['user' => 'user'], 'actor', [
 				'You added {user}',
-				['actor' => ['id' => 'actor'], 'user' => ['id' => 'user']],
+				['actor' => ['id' => 'actor', 'type' => 'user'], 'user' => ['id' => 'user', 'type' => 'user']],
 			]],
 			['user_removed', ['user' => 'user'], null, [
 				'{actor} removed {user}',
-				['actor' => ['id' => 'actor'], 'user' => ['id' => 'user']],
+				['actor' => ['id' => 'actor', 'type' => 'user'], 'user' => ['id' => 'user', 'type' => 'user']],
 			]],
 			['user_removed', ['user' => 'user'], 'recipient', [
 				'{actor} removed {user}',
-				['actor' => ['id' => 'actor'], 'user' => ['id' => 'user']],
+				['actor' => ['id' => 'actor', 'type' => 'user'], 'user' => ['id' => 'user', 'type' => 'user']],
 			]],
 			['user_removed', ['user' => 'actor'], 'actor', [
 				'{actor} left the conversation',
-				['actor' => ['id' => 'actor'], 'user' => ['id' => 'actor']],
+				['actor' => ['id' => 'actor', 'type' => 'user'], 'user' => ['id' => 'actor', 'type' => 'user']],
 			]],
 			['user_removed', ['user' => 'user'], 'user', [
 				'{actor} removed you',
-				['actor' => ['id' => 'actor'], 'user' => ['id' => 'user']],
+				['actor' => ['id' => 'actor', 'type' => 'user'], 'user' => ['id' => 'user', 'type' => 'user']],
 			]],
 			['user_removed', ['user' => 'user'], 'actor', [
 				'You removed {user}',
-				['actor' => ['id' => 'actor'], 'user' => ['id' => 'user']],
+				['actor' => ['id' => 'actor', 'type' => 'user'], 'user' => ['id' => 'user', 'type' => 'user']],
 			]],
 			['moderator_promoted', ['user' => 'user'], null, [
 				'{actor} promoted {user} to moderator',
-				['actor' => ['id' => 'actor'], 'user' => ['id' => 'user']],
+				['actor' => ['id' => 'actor', 'type' => 'user'], 'user' => ['id' => 'user', 'type' => 'user']],
 			]],
 			['moderator_promoted', ['user' => 'user'], 'recipient', [
 				'{actor} promoted {user} to moderator',
-				['actor' => ['id' => 'actor'], 'user' => ['id' => 'user']],
+				['actor' => ['id' => 'actor', 'type' => 'user'], 'user' => ['id' => 'user', 'type' => 'user']],
 			]],
 			['moderator_promoted', ['user' => 'user'], 'user', [
 				'{actor} promoted you to moderator',
-				['actor' => ['id' => 'actor'], 'user' => ['id' => 'user']],
+				['actor' => ['id' => 'actor', 'type' => 'user'], 'user' => ['id' => 'user', 'type' => 'user']],
 			]],
 			['moderator_promoted', ['user' => 'user'], 'actor', [
 				'You promoted {user} to moderator',
-				['actor' => ['id' => 'actor'], 'user' => ['id' => 'user']],
+				['actor' => ['id' => 'actor', 'type' => 'user'], 'user' => ['id' => 'user', 'type' => 'user']],
 			]],
 			['moderator_demoted', ['user' => 'user'], null, [
 				'{actor} demoted {user} from moderator',
-				['actor' => ['id' => 'actor'], 'user' => ['id' => 'user']],
+				['actor' => ['id' => 'actor', 'type' => 'user'], 'user' => ['id' => 'user', 'type' => 'user']],
 			]],
 			['moderator_demoted', ['user' => 'user'], 'recipient', [
 				'{actor} demoted {user} from moderator',
-				['actor' => ['id' => 'actor'], 'user' => ['id' => 'user']],
+				['actor' => ['id' => 'actor', 'type' => 'user'], 'user' => ['id' => 'user', 'type' => 'user']],
 			]],
 			['moderator_demoted', ['user' => 'user'], 'user', [
 				'{actor} demoted you from moderator',
-				['actor' => ['id' => 'actor'], 'user' => ['id' => 'user']],
+				['actor' => ['id' => 'actor', 'type' => 'user'], 'user' => ['id' => 'user', 'type' => 'user']],
 			]],
 			['moderator_demoted', ['user' => 'user'], 'actor', [
 				'You demoted {user} from moderator',
-				['actor' => ['id' => 'actor'], 'user' => ['id' => 'user']],
+				['actor' => ['id' => 'actor', 'type' => 'user'], 'user' => ['id' => 'user', 'type' => 'user']],
+			]],
+			['guest_moderator_promoted', ['session' => 'moderator'], null, [
+				'{actor} promoted {user} to moderator',
+				['actor' => ['id' => 'actor', 'type' => 'user'], 'user' => ['id' => 'moderator', 'type' => 'guest']],
+			]],
+			['guest_moderator_promoted', ['session' => 'moderator'], 'recipient', [
+				'{actor} promoted {user} to moderator',
+				['actor' => ['id' => 'actor', 'type' => 'user'], 'user' => ['id' => 'moderator', 'type' => 'guest']],
+			]],
+			['guest_moderator_promoted', ['session' => 'moderator'], 'guest::user', [
+				'{actor} promoted {user} to moderator',
+				['actor' => ['id' => 'actor', 'type' => 'user'], 'user' => ['id' => 'moderator', 'type' => 'guest']],
+			]],
+			['guest_moderator_promoted', ['session' => 'moderator'], 'guest::moderator', [
+				'{actor} promoted you to moderator',
+				['actor' => ['id' => 'actor', 'type' => 'user'], 'user' => ['id' => 'moderator', 'type' => 'guest']],
+			]],
+			['guest_moderator_promoted', ['session' => 'moderator'], 'actor', [
+				'You promoted {user} to moderator',
+				['actor' => ['id' => 'actor', 'type' => 'user'], 'user' => ['id' => 'moderator', 'type' => 'guest']],
+			]],
+			['guest_moderator_demoted', ['session' => 'moderator'], null, [
+				'{actor} demoted {user} from moderator',
+				['actor' => ['id' => 'actor', 'type' => 'user'], 'user' => ['id' => 'moderator', 'type' => 'guest']],
+			]],
+			['guest_moderator_demoted', ['session' => 'moderator'], 'recipient', [
+				'{actor} demoted {user} from moderator',
+				['actor' => ['id' => 'actor', 'type' => 'user'], 'user' => ['id' => 'moderator', 'type' => 'guest']],
+			]],
+			['guest_moderator_demoted', ['session' => 'moderator'], 'guest::user', [
+				'{actor} demoted {user} from moderator',
+				['actor' => ['id' => 'actor', 'type' => 'user'], 'user' => ['id' => 'moderator', 'type' => 'guest']],
+			]],
+			['guest_moderator_demoted', ['session' => 'moderator'], 'guest::moderator', [
+				'{actor} demoted you from moderator',
+				['actor' => ['id' => 'actor', 'type' => 'user'], 'user' => ['id' => 'moderator', 'type' => 'guest']],
+			]],
+			['guest_moderator_demoted', ['session' => 'moderator'], 'actor', [
+				'You demoted {user} from moderator',
+				['actor' => ['id' => 'actor', 'type' => 'user'], 'user' => ['id' => 'moderator', 'type' => 'guest']],
 			]],
 			['file_shared', ['share' => '42'], null, [
 				'{file}',
-				['actor' => ['id' => 'actor'], 'file' => ['id' => 'file-from-share']],
+				['actor' => ['id' => 'actor', 'type' => 'user'], 'file' => ['id' => 'file-from-share']],
 			]],
 			['file_shared', ['share' => '42'], 'recipient', [
 				'{file}',
-				['actor' => ['id' => 'actor'], 'file' => ['id' => 'file-from-share']],
+				['actor' => ['id' => 'actor', 'type' => 'user'], 'file' => ['id' => 'file-from-share']],
 			]],
 			['file_shared', ['share' => '42'], 'actor', [
 				'{file}',
-				['actor' => ['id' => 'actor'], 'file' => ['id' => 'file-from-share']],
+				['actor' => ['id' => 'actor', 'type' => 'user'], 'file' => ['id' => 'file-from-share']],
 			]],
 			['file_shared', ['share' => ShareNotFound::class], null, [
 				'{actor} shared a file which is no longer available',
-				['actor' => ['id' => 'actor']],
+				['actor' => ['id' => 'actor', 'type' => 'user']],
 			]],
 			['file_shared', ['share' => InvalidPathException::class], 'recipient', [
 				'{actor} shared a file which is no longer available',
-				['actor' => ['id' => 'actor']],
+				['actor' => ['id' => 'actor', 'type' => 'user']],
 			]],
 			['file_shared', ['share' => NotFoundException::class], 'actor', [
 				'You shared a file which is no longer available',
-				['actor' => ['id' => 'actor']],
+				['actor' => ['id' => 'actor', 'type' => 'user']],
 			]],
 		];
 	}
@@ -333,13 +373,18 @@ public function dataParseMessage(): array {
 	 * @param array $expected
 	 */
 	public function testParseMessage(string $message, array $parameters, $recipientId, array $expected) {
-		if ($recipientId) {
+		if ($recipientId && strpos($recipientId, 'guest::') === false) {
 			$recipient = $this->createMock(IUser::class);
 			$recipient->expects($this->atLeastOnce())
 				->method('getUID')
 				->willReturn($recipientId);
+			$sessionId = null;
+		} else if ($recipientId) {
+			$recipient = null;
+			$sessionId = substr($recipientId, strlen('guest::'));
 		} else {
 			$recipient = null;
+			$sessionId = null;
 		}
 
 		/** @var IComment|MockObject $comment */
@@ -351,16 +396,21 @@ public function testParseMessage(string $message, array $parameters, $recipientI
 				'parameters' => $parameters,
 			]));
 
-		$parser = $this->getParser(['getActor', 'getUser', 'parseCall', 'getFileFromShare']);
+		$parser = $this->getParser(['getActor', 'getUser', 'getGuest', 'parseCall', 'getFileFromShare']);
 		$parser->expects($this->once())
 			->method('getActor')
 			->with($comment)
-			->willReturn(['id' => 'actor']);
+			->willReturn(['id' => 'actor', 'type' => 'user']);
 		$parser->expects($this->any())
 			->method('getUser')
 			->with($parameters['user'] ?? 'user')
-			->willReturn(['id' => $parameters['user'] ?? 'user']);
+			->willReturn(['id' => $parameters['user'] ?? 'user', 'type' => 'user']);
+		$parser->expects($this->any())
+			->method('getGuest')
+			->with($parameters['session'] ?? 'guest')
+			->willReturn(['id' => $parameters['session'] ?? 'guest', 'type' => 'guest']);
 		self::invokePrivate($parser, 'recipient', [$recipient]);
+		self::invokePrivate($parser, 'sessionId', [$sessionId]);
 
 		if ($message === 'call_ended') {
 			$parser->expects($this->once())
@@ -424,12 +474,12 @@ public function testParseMessageThrows($return) {
 		$parser->expects($this->any())
 			->method('getActor')
 			->with($comment)
-			->willReturn(['id' => 'actor']);
+			->willReturn(['id' => 'actor', 'type' => 'user']);
 
 		$parser->parseMessage($comment);
 	}
 
-	public function testSetUserInfoGuestToUser() {
+	public function testSetUserInfoEmptyToUser() {
 		/** @var IUser $user */
 		$user = $this->createMock(IUser::class);
 		/** @var IL10N $l */
@@ -437,9 +487,11 @@ public function testSetUserInfoGuestToUser() {
 
 		$parser = $this->getParser();
 		$this->assertNull(self::invokePrivate($parser, 'recipient'));
+		$this->assertNull(self::invokePrivate($parser, 'sessionId'));
 		$this->assertSame($this->l, self::invokePrivate($parser, 'l'));
 		$parser->setUserInfo($l, $user);
 		$this->assertSame($user, self::invokePrivate($parser, 'recipient'));
+		$this->assertNull(self::invokePrivate($parser, 'sessionId'));
 		$this->assertSame($l, self::invokePrivate($parser, 'l'));
 	}
 
@@ -457,13 +509,15 @@ public function testSetUserInfoUser1ToUser2() {
 
 		$parser = $this->getParser();
 		$this->assertSame($user1, self::invokePrivate($parser, 'recipient'));
+		$this->assertNull(self::invokePrivate($parser, 'sessionId'));
 		$this->assertSame($this->l, self::invokePrivate($parser, 'l'));
 		$parser->setUserInfo($l, $user2);
 		$this->assertSame($user2, self::invokePrivate($parser, 'recipient'));
+		$this->assertNull(self::invokePrivate($parser, 'sessionId'));
 		$this->assertSame($l, self::invokePrivate($parser, 'l'));
 	}
 
-	public function testSetUserInfoUserToGuest() {
+	public function testSetUserInfoUserToEmpty() {
 		/** @var IUser $user1 */
 		$user = $this->createMock(IUser::class);
 		/** @var IL10N $l */
@@ -475,9 +529,41 @@ public function testSetUserInfoUserToGuest() {
 
 		$parser = $this->getParser();
 		$this->assertSame($user, self::invokePrivate($parser, 'recipient'));
+		$this->assertNull(self::invokePrivate($parser, 'sessionId'));
 		$this->assertSame($this->l, self::invokePrivate($parser, 'l'));
 		$parser->setUserInfo($l, null);
 		$this->assertNull(self::invokePrivate($parser, 'recipient'));
+		$this->assertNull(self::invokePrivate($parser, 'sessionId'));
+		$this->assertSame($l, self::invokePrivate($parser, 'l'));
+	}
+
+	public function testSetGuestInfoEmptyToGuest() {
+		/** @var IL10N $l */
+		$l = $this->createMock(IL10N::class);
+
+		$parser = $this->getParser();
+		$this->assertNull(self::invokePrivate($parser, 'recipient'));
+		$this->assertNull(self::invokePrivate($parser, 'sessionId'));
+		$this->assertSame($this->l, self::invokePrivate($parser, 'l'));
+		$parser->setGuestInfo($l, 'session');
+		$this->assertNull(self::invokePrivate($parser, 'recipient'));
+		$this->assertSame('session', self::invokePrivate($parser, 'sessionId'));
+		$this->assertSame($l, self::invokePrivate($parser, 'l'));
+	}
+
+	public function testSetGuestInfoGuest1ToGuest2() {
+		/** @var IL10N $l */
+		$l = $this->createMock(IL10N::class);
+
+		$parser = $this->getParser();
+		self::invokePrivate($parser, 'sessionId', ['session1']);
+
+		$this->assertNull(self::invokePrivate($parser, 'recipient'));
+		$this->assertSame('session1', self::invokePrivate($parser, 'sessionId'));
+		$this->assertSame($this->l, self::invokePrivate($parser, 'l'));
+		$parser->setGuestInfo($l, 'session2');
+		$this->assertNull(self::invokePrivate($parser, 'recipient'));
+		$this->assertSame('session2', self::invokePrivate($parser, 'sessionId'));
 		$this->assertSame($l, self::invokePrivate($parser, 'l'));
 	}
 
diff --git a/tests/php/Notification/NotifierTest.php b/tests/php/Notification/NotifierTest.php
index 4342c9ac9aa..7363c37f696 100644
--- a/tests/php/Notification/NotifierTest.php
+++ b/tests/php/Notification/NotifierTest.php
@@ -485,7 +485,7 @@ public function testPrepareMention($roomType, $subjectParameters, $displayName,
 			->willReturn($comment);
 		$this->messageParser->expects($this->once())
 			->method('parseMessage')
-			->with($comment)
+			->with($room, $comment)
 			->willReturn(['Hi {mention-user1}', [
 				'mention-user1' => [
 					'type' => 'user',