SIP REGISTER request: How to define an (addditional) custom contact in linphonerc to be used in SIP REGISTER requests

[hobbit378]

@Viish

My question:

Is it possible to define an (addditional/custom) contact URI in linphonerc to be used during SIP REGISTER

What I want to achieve:

Assuming SIP account settings in linphone-android client are set to enable registration, thus, the linphone-android client periodically sends SIP REGISTER requests to the SIP Proxy of the SIP provider. Within the REGISTER request it transmits the actual IP address of my device as 'contact:' information.

Is it possible - by means of according settings in linphonerc - to cause linphone-android SIP client
a) to add additional SIP URIs to be included as further additional/alternative 'contact:' headers in the SIP REGISTER request and/or
b) also to completly replace sending the device IP as 'contact:' information. with a custom alternative contact: URI
c) if the answer to a) or b) is yes, can you please point me to documentation regarding the pertinent settings and/or according examples

Background:

I want to e.g. add the SIP URI of my Linphone account as additional contact: information.
As my other SIP provider does not support sending PUSH notifications to linphone-android client, if I would be able to register my sip:xyz@linphone.org account as additional contact information, the provider would forthwith send INVITE requests also via the linphone.org SIP proxy which supports sending PUSH notifications.