VoLTE on de-Googled Samsung devices: perhaps there is light at the end of the tunnel

About a year ago I wrote of my disappointment and annoyance that lack of VoLTE support rendered Lineage OS and other Google-free custom ROMs essentially useless on Samsung devices. This was a crying shame because Samsung makes great mobile handsets, which are well-supported by a number of de-Googled Android implementations.

Voice-over-LTE (VoLTE) is part of the new “Internet Media Services” (IMS) standard for 4G and 5G mobile networks, dealing with voice calling using Internet protcols. In the UK, and probably elsewhere, there is no viable alternative to VoLTE, if you want reliable voice calls. Since all the 3G masts have been shut down, the fallback – such as it is – is to ancient 2G services, many of which are very flaky now.

My go-to mobile handset was the Galaxy Note 9 – the last top-of-the-range Samsung model to have a 3.5mm headset jack. It also has expandable storage – to 1Tb at least – and a natty little stylus. In 2026 you can buy a pristine refurbished example for about £100, and you’d have to spend a lot of money to get better performance from a new handset. That I could no longer use this device, nor any of my other Samsung handsets, was a constant source of irritation to me. Of course, the stock Samsung firmware has an IMS implementation, which Samsung is keeping to itself, but nobody with the slightest concern about on-line privacy should be using that: Samsung’s flavour of Android adds its own privacy-destroying anti-features to Google’s well-known data-siphoning.

So, with great reluctance, I put my Samsung handsets away and investigated alternatives from Sony, Google, Motorola, and others. While I had reasonable success with all of these, no cellphone in my price range could compete with Samsung for performance or features.

Sadly, a year ago I thought this was the end of the line for Lineage OS on Samsung, because nobody was going to write a complete IMS implementation from scratch, along with all the supporting infrastructure. It seems, however, that I had underestimated the Android hacking community. While there are still problems to overcome, we’re starting to see IMS implementations that mostly work.

So far as I can tell (and I confess that I haven’t researched this in depth), the first viable open-source implementation of IMS was “phhims” by Pierre-Hugues Husson. More recently, somebody going by the nickname of “Krazey” has developed this into a more complete implementation, and has also released various (unofficial) custom builds of LineageOS that include the new code. I’m using the Android 24 build for my Note 9.

You can also find instructions and scripts for integrating phhims into a rooted handset using a Magisk module definition, like this example from “zombienerd8000”. This method shouldn’t require a complete, custom Lineage build but, in practice, it does seem to be tied to a specific Android version.

I couldn’t make any of these scripts work on my Note 9 with the latest official release of Lineage OS (based on Android 16) – I think they need Android 20 (?) or later. The unofficial Note 9 Lineage build created by Krazey is based on Android 22 and this does work – at least in my early tests. Installing it is no different to installing one of the official Lineage releases: easy enough if you don’t mind wiping all your data and starting clean, horrible otherwise.

It isn’t just the lack of IMS support that makes Samsung devices unworkable for VoLTE: they have problems with audio routing as well. A viable solution must tackle the audio issues as well as support the IMS specifications. The various implementations I’ve looked at all purport to do this.

So I can make and receive voice calls using 4G services, and the audio works in both directions, nearly every time. The handset definitely isn’t falling back on 2G services, because there aren’t any in my area. Right now, my enthusiasm is slightly tempered by the fact that battery drain with this unofficial Lineage release seems a bit worse than with earlier, official ones. Of course, whether this is due to the IMS support or to something else entirely, I really don’t know. What I do know is that my Samsung Note 9 is back in my pocket, and I’m happy to have it there, despite the occasional glitches.

Support isn’t limited to the Note 9: there are (unofficial) Lineage OS builds for the Galaxy “S” range as well, from the S10 all the way to the S24.

I have to point out that the work of integrating an open-source IMS implementation into Lineage OS (and similar) is still at a relatively early stage. So far as I know the support I’ve been testing isn’t available in any official Lineage OS release, or in any other mainstream custom ROM. To try it out, you’ll need to install firmware from an unofficial source, which could have all kinds of security and privacy holes. Of course, that’s true of any Android custom ROM – but it’s true of most vendor’s stock firmware, too: the security and privacy limitations associated with vendor firmware are, of course, by design.

Still, trying out this kind of software is perhaps not advisable if you really need your cellphone to offer 100% reliability, or if you’re using it to store military secrets.

I can’t predict the future of IMS support in Lineage OS, et al. I hope that the work done so far will find its way into mainstream releases before too long, so more people can test them. VoLTE support is notoriously carrier-dependent, so we do need a lot more testing.

Still, what I’ve seen so far gives me at least some grounds for optimism… at last.