Context: IMS means VoLTE + VoWifi (+ other stuff), which is how you do calls and SMS over LTE, which is mostly "just" SIP
This move of Voice and SMS to an IP protocol is IMO pretty interesting for opensource community because it means we can largely reduce the footprint of the modem to "just" giving IP connections.
The main contributors to opensource IMS client should to be "secure smartphones", long before people doing "let me opensource my baseband", because running a super-privileged SIP client is very dangerous (even Pixels, no matter the OS, got security flaws in it few months ago), but that's clearly not what I'm seeing. (There are also other security considerations justifying an opensource IMS client, like forcing the encryption of VoLTE)
As someone who spend a lot of time making an Android opensource IMS client ( https://github.com/phhusson/ims ), this wiki page isn't really news: I've had this setup (Doubango IMS client, which is a C embedded-leaning opensource client + VoWifi tunnel) running on my desktop using an Android smartphone as a SIM card reader more than a year ago ( https://github.com/phhusson/doubango/blob/master/README-phh ), which is well, just the same age as that wiki page. Except that I've been using it over real carriers, not just software ones.
If someone has some time to spend on it, for GNU/Linux smartphones, Doubango IMS client should be pretty straightforward to get to work, what's missing is "only" plumbing.
Either way, if the people who are working on that are here, please say hi so we can share our war stories :-)
I have IMS war stories, but they're from when we started deploying core services up to 2008 (from pre-IMS SIP and cobbled together Asterisk and Cisco Callmanager bridges to full-on 1st gen voice core, with VoLTE coming later as we replaced the radio layer, and VoWifi as a stopgap for operators with poor coverage).
I did a lot of handset testing, but mostly on the radio and broadband side, and to be honest I wouldn't mind seeing a good, auditable OSS stack (with attestation and SBOMs) since there are so many potential security issues in handsets these days...
This move of Voice and SMS to an IP protocol is IMO pretty interesting for opensource community because it means we can largely reduce the footprint of the modem to "just" giving IP connections.
The main contributors to opensource IMS client should to be "secure smartphones", long before people doing "let me opensource my baseband", because running a super-privileged SIP client is very dangerous (even Pixels, no matter the OS, got security flaws in it few months ago), but that's clearly not what I'm seeing. (There are also other security considerations justifying an opensource IMS client, like forcing the encryption of VoLTE)
As someone who spend a lot of time making an Android opensource IMS client ( https://github.com/phhusson/ims ), this wiki page isn't really news: I've had this setup (Doubango IMS client, which is a C embedded-leaning opensource client + VoWifi tunnel) running on my desktop using an Android smartphone as a SIM card reader more than a year ago ( https://github.com/phhusson/doubango/blob/master/README-phh ), which is well, just the same age as that wiki page. Except that I've been using it over real carriers, not just software ones.
If someone has some time to spend on it, for GNU/Linux smartphones, Doubango IMS client should be pretty straightforward to get to work, what's missing is "only" plumbing.
Either way, if the people who are working on that are here, please say hi so we can share our war stories :-)