[Feature Request] Support Wi-Fi Calling on supported iCloud-connected devices

[mtalexan]

Some phone carriers (most in the US and Canada), allow iPhone devices, with thier SIM/eSIM in them and connected to an iCloud account, to use WiFi calling on supported iCloud-connected devices. This allows non-iPhone devices to perform WiFi calling via thier iCloud account, including if the iPhone itself is off.

Given that there are only two consistently working ways to have a registered phone number with OpenBubbles:

1. Use an iPhone on iOS <17.5, set it up as a validation relay, and use OpenBubbles to spoof the iPhone
2. Put your actual SIM/eSIM in an iPhone, connect it to iCloud, enable message forwarding, and register your OpenBubbles as a Mac connected to the same iCloud account (registering as a second iPhone won't forward shortcode messages like it will with a Mac registration)

Case 2 supports having all your SMS/MMS, optionally RCS, and iMessage chats together, and also provides a way to get RCS indirectly on a degoogled device or computer. But runs into the issue that while you can forward your incoming calls to another number, there really isn't any solution for supporting outgoing calls from your same number. This "Wi-Fi calling in supported iCloud-connected devices" feature would solve that, eliminate the need to setup call forwarding, and allow computers to get the same calling support as a Mac has.

Caveat: I have no idea what additional authentication might be involved to be a "supported iCloud-connected device", or if that's even possible to spoof sufficiently.

[MR-UNI]

This cannot be implemented as it is not within Apple's nor OpenBubble's scope. the reason being is that this works on the carrier's side. your phone (your actual phone you use daily), is authenticated with your carrier, they know what cellular device you are using, they know what IMEI that device holds, if you were to attempt to enable wifi calling on a device that is not your phone, the carrier will reject that.

[mtalexan]

I think you mistake what I'm requesting here, though maybe I'm wrong about the mechanics.

Regular WiFi calling is indeed a carrier feature that requires the SIM card for the carrier and simply does the authentication it would normally do via cell tower over WiFi instead. That wouldn't be possible.

However, there is a separate "WiFi calling in supported iCloud-connected devices" feature where even a Mac laptop can make a WiFi call thru iCloud as if it was your iPhone. It looked at first glance as if the iCloud might be acting as a proxy for the carrier authentication, using the iPhone and it's SIM card that's simultaneously connected to iCloudfor the carrier-specific authentication.