Could the Librem 5 ever support "WiFi calling"? (UMA/GAN)


I find myself wondering if the Librem 5 will ever support WiFi calling, also known as “GAN” or “UMA” according to Wikipedia. Most new phones seem to support this.

For those who don’t know, WiFi calling essentially replaces the cellular radio link with a tunnel into your carrier’s network over WiFi and the Internet, in situations when you have WiFi but no or poor cellular coverage. You can use it to make and receive calls and to send and receive SMS and MMS messages, which are billed to your normal account using your normal number.

Does anyone have any idea about what it would take to support WiFi calling, and how likely or unlikely it is for the Librem 5 to ever support it? For example, does it require any binary blobs or non-disclosure agreements, or just open standards and access to the SIM? Does it require tight coupling between the WiFi, CPU and baseband, or can it be done with the Librem design? Has the Purism team looked into it at all?

I suppose it might be related, in terms of how it works, to VoLTE, which I guess prompts a different question about whether that will be possible to support.

Of course, the Librem 5 will be able to use Matrix for VoIP, but that covers slightly different use cases compared to WiFi calling.

For me, this is a “nice to have” rather than a necessity, but it is something that I would probably make use of, given the extent to which buildings often interfere with signals.


Matrix support VOIP, which can be used on WiFi. I fail to see the difference between Wi-Fi calling and VOIP.


“WiFi calling” is a term that’s used specifically to refer to a kind of VOIP that is provided by your cellular network provider (carrier). By definition, it connects to servers provided by the cellular network provider and authenticates using the SIM card in the phone.

Its primary benefit is seamlessly improved coverage for the conventional cellular service into all locations where the device has access to the Internet using WiFi, using the same telephone number and the same billing account, with no setup or configuration, and no need to load a separate application.

This contrasts with other VOIP services, which tend to have advantages such as low cost, privacy and flexibility, but cannot normally make direct use of a telephone number provided by your cellular network provider, and tend to operate as a separate service.

Of course, you can achieve functionality similar to WiFi calling by using a standalone VOIP service as your primary telephone service, but it requires a different arrangement of service providers. My question is specifically about WiFi calling.

I make no claim about which solution is best. I think both have valid use cases.


Further, WiFI calling (at least with the carriers I use) allows one to place calls that roam from WiFi to cell to WiFI and these calls are to the PSTN and the person on the other end neither knows nor cares that I’m using WiFi calling . . . so definitely not Matrix.


Since I have no cell signal from ANY carrier for about a mile radius right around my house I HAVE to have wifi calling ability. I have an AT&T femtocell now that works well when it’s up but it crashes fairly often anymore. So I’d really like to purchase a Librem 5 but won’t be able to unless it supports wifi calling.

As my current phone is dead I have to buy a new phone now. Do I buy a cheap one while I wait for a wifi calling enabled Librem 5 or do I buy a nice one since wifi calling won’t be supported on the Librem 5???

ANY help answering this question would be GREATLY appreicated!



I’m interested in this as well


I see that WiFi calling is also being called “VoWiFi”, to add to its existing profusion of names.


Skype would provide this if you pay for a Skype out number, etc. Not what the OP is after but a solution nonetheless.