PWA tel protocol handler

This PWA registers as a tel protocol handler. This app will be launched any time a user clicks a link of the following standard form on any web site.

Example;

Click to dial and invoke the PWA: +61400000000

Installation

1. Visit the link where this code will be deployed
2. Click '...' in top right hand corner of a Chromium browser
3. Hover over apps, a little menu box should appear
4. Click "install this site as an app"
5. Accept defaults
6. It will launch the app, close the app.

Installation verification

Check app installed:

1. Hover over apps, select view app's
2. The installed app should appear

Check Manifest:

1. F12 in browser, application tab -> manifest
2. Scoll down and check protocol handler registered

Check Windows has registered the Telephony Provider:

1. settings->apps->default apps->scroll down->set app by protocol
2. Scoll down the list of protocols to tel:
3. The app should appear as the tel: protocol handler

Testing

Click on of the phone numbers on the PWA page, or any web site that has clickable phone numbers

What is a PWA

PWAs also have many of the benefits of platform-specific apps, including:

PWAs can be installed on the device. This means:

• The PWA can be installed from platform's app store or installed directly from the web.
• The PWA can be installed like a platform-specific app, and can customize the install process.
• Once installed, the PWA gets an app icon on the device, alongside platform-specific apps.
• Once installed, the PWA can be launched as a standalone app, rather than a website in a browser.

PWAs can operate in the background and offline: a typical website is only active while the page is loaded in the browser. A PWA can:

• Work while the device does not have network connectivity.
• Update content in the background.
• Respond to push messages from the server.
• Display notifications using the OS notifications system.
• PWAs can use the whole screen, rather than running in the browser UI.
• PWAs can be integrated into the device, registering as share targets and sources, and accessing device features.
• PWAs can be distributed in app stores, as well as openly via the web.

For a good description of what is a PWA see : https://developer.mozilla.org/en-US/docs/Web/Progressive_web_apps/Guides/What_is_a_progressive_web_app

This implementation

This implementation is not a true PWA as it does not have a service worker. Its only purpose is to act as a tel: protocol handler and doesn't need a service worker to respond to background events or provide capability when the app is launched offline.

It does use the standard PWA manifest file which via a web host. The manifest has the following protocol handler section as follows:

  "protocol_handlers": [
    {
      "protocol": "tel",
      "url": "/click-to-dial/tel_pwa?num=%s"
    }
  ]