At first, man thinks he controls the modem.

But after the 20th reboot, man learns the modem controls him.

— Epictetus

So here it is! working VoLTE calls with audio on linux!

What a rollercoaster it has been i’ll tell you that.

The frequency between my previous posts was only a few days, as you can see from the time since my last post this has been a far harder project.

But a successful one!

Now fully powered trough my new imsd project:

https://forgejo.catcrafts.net/Catcrafts/imsd

As i said in a my previous comment no matter what i did the regular modem route wasn’t working, so i had to come up with my own.

This has several advantages however, call audio is now just routed trough wireplumber & pipewire, so its integrated much better.

Both inbound and outbound calls work.

How do i get this???

The patient route is waiting until my patches get accepted upstream, a few already have and are coming in 7.3 probably (pmos runs 7.0 currently still oof), a few will probably take longer, 7.4 or beyond.

but for the ones that want to jump right on ive published everything on my forgejo:

https://forgejo.catcrafts.net/Catcrafts

I will soon be publishing a shell script that does the entire installation soon for easy installation.

Sadly there is no way to just plug in an android and do it, so there are still a few manual steps needed, but i believe the path to adoption is reducing friction as much as possible, so ill do my best to make it as easy as possible to use.

imsd

So what is an “imsd”?

its a full userspace implementation of the IMS protocol, which drives VoLTE (4G) calls.

Normally the modem firmware drives this, but this is quite difficult to work with, now it runs fully via a standard daemon on linux!

Along with several d-bus helpers that integrate it with standard plasma-dialer.

if made a APKBUILD for pmos that is mutually exclusive with 81voltd, and loads imsd instead. so installation should be easy.

Now will this actually work?

That’s where you come in!

I am just one guy with one phone with one carrier.

I can say it works on the Fairphone 6 with KPN. it might work with other carriers and other Qualcomm phones aswell, so potentially this could work for the entire linux phone ecosystem, but i have no way to test that.

If you end up trying it, no matter if it works or doesn’t work, please send me a message or open a PR, then we can make sure it works for everyone!

donations

I really was surprised when people asked me this, i just see myself as a guy doing this in his free time, “why would people want to send donations to me?” i thought.

I still stand by my previous point, i have a job, and this project costs me nothing except for time, i don’t have any costs. So i felt kinda guilty receiving money from people.

But i would much rather spend my time making software that benefits society instead of the B2B stuff i do at my job.

I really feel greedy for saying this, but if you want to send me a thank you then that is now possible at: https://bunq.me/catcrafts

Please don’t feel any pressure to do this, doesn’t matter what i get im still continuing with this bring-up. And if you don’t want to donate to me there are many linux organizations that could really use the support! In my eyes we are all in the same boat with the same goal.

If you do decide to, and i cannot express my gratitude enough if you do, please write in the description that it’s a donation, as this makes tax easier.

What’s next?

Ive got a bunch more stuff coming soon, while i haven’t posted here in quite a while i’ve been plenty busy on the mailing list:

So except some more posts soon.

Bonus round

Having fully working hardware is great, but a phone that has no apps is pointless for most people, so i would like to start a discussion in the comments.

What apps do you need that are preventing you from switching to mobile linux?