Clarification regarding multiple phoneNumbers registration

[stroncoso]

Problem description

⚠️ Clarification needed

• Should we include phoneNumber on the POST registration action?
• How to identify the phoneNumber included on the POST response if the user has multiple linked?

There's a problem when trying to handle several MSISDN (phoneNumbers) on the same physical device. This use case appears when a user has multiple SIMs, and he wants to use it on the same device. The user is, in fact, allowed to use several phoneNumbers. This was not discussed previously. The network could know if the user is allowed to use each of them, but it will not be clear or completely out of control to discriminate them.

Let's go with an example:

Alice has 3 phone numbers: 2x SIMs (work and personal), and an eSIM for travelling
She bought a new iPad and wants to use his personal phone number on it.
Later when taking a holiday, he wants to use, in paralel, the eSIM.

Questions in this use case:

• How can the app specify and register only one phone number?
• Are we going to enforce the 1:1 relationship between a deviceId and a phoneNumber. In that case, where is this configured?

Expected behavior

• Adding a phoneNumber field on the Registration API POST /session action.
  This will clearly identify the phone number to tie to the registrationId.
  The network will allow or not the registration for that number to that device (JWT or other sources)

Alternative solution

• Keep the Registration API POST /session action as it is, and infer the phoneNumber replied.
  This will keep the deviceId <-> phoneNumber on the network. Developer can not control it.
  The network will allow or not the registration for that device (JWT or other sources), bringing the phoneNumber as the response

Additional context

• We have a consensus on the fact that registrationId has a 1:1 relationship with the tuple (deviceId,phoneNumber)
• Current API description does not include phoneNumber on the POST /session action of the WebRTC Registration API. This number is returned on a sucesful registration.
  • Check API here: WebRTC Registration API r2.2