FP2 VoLTE again

As the UMTS (3G) service in Germany is continually being reduced (licences start to expire, and mobile providers tend to dismantle UMTS when upgrading their base stations to 5G) the need to be able to place calls via LTE rises steadily. Currently, the number of base stations running UMTS is dropping constantly! Without VoLTE, fairphone customers could end up with no telephony services in Germany! There are already places where only good old GSM is available to place calls.

The future of GSM (2G) as a fallback is only secured for a couple of years, but the end of 3G/UMTS is coming very soon!

Reports can be found on the net that Telekom and Vodafone customers (biggest and second biggest networks) managed to enable VoLTE on fairphones, but the need arises that Fairphone integrates the Telefonica IMS data. Without that, Telefonica customers cannot use VoLTE on the Fairphone.

Telefonica issued a press release in July that they enabled VoLTE to ALL customers of Telefonica, regardless of the brand of Telefonica they use (the most common are O2 and E-Plus, but there are numerous others). So how can we bring the developers of Fairphone Android AND (!) Fairphone Open OS, those two are officially supported OS on the FP2 to integrate the necessary IMS data?

Currently the devs are working to bring us Pie (Android 9), which I applaud! When working on the code, could they please assign a tiny little manpower to upgrading IMS data to include all three big networks in Germany, which is the biggest single market in the EU?



I’ve raised a question to Fairphone support a while ago if the VoLTE code can be made public to be included e.g. in LineageOS and others, but didn’t get an answer so far.

I imagine it’s also not just done with the IMS relevant data but also depending on working codecs for which I hope, some of them may be open source, or at least a free license. Lets see what are the chances.

When I type *#*#4636#*#* in the dialler, I see lots of options, and sliders for “VoLTE identification”, “Videocalls configured” and “WiFi calls configured”, all of them are greyed out. So it looks like the app is there, but the IMS data is lacking. There are reports from users running an FP2 with FPOS on a US SIM card, here in the FP forum, that had those sliders operational, thus being able to call via VoLTE…
Edit: Hm, this forum can’t handle this string, so I spell it out: Star Hash Star Hash 4636 hash star hash star.

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I think it works if you put it between backticks (``)


I assume you are specifically talking about FP2 here, right? I expect IMS data is not there yet, because this will be added by the telco providers in the final version, as for FP3 (if the codec is supported). The question for me is: Is it allowed to be released to the public or is it secret?

You can use the html codes < pre >…< /pre > for this (or backticks as Ingo said).

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The IMS data itself is public:

Network providers can limit the number of phone manufacturers who can see the network’s config data. But Telefonica is listed as a network provider, Telefonica has publicly announced “VoLTE for everybody”, and Telefonica offers the Fairphone 3 officially. So this means Telefonica has granted Fairphone (as a company) access to it’s IMS data. So Fairphone knows everything that is needed here…

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This issue now becomes urgent.

My network provider (Telefonica / O2) just sent me an SMS that they will shut down 3G services in the course of 2021, and “your device does not support 4G”. That came while I was logged into O2s 4G net :slight_smile: Obviously they SAY 4G but MEAN VoLTE.

Now this issue becomes pressing. Does anyone from Fairphone read here in the forum?

WE NEED VOLTE N O W or our beloved Fairphones 2 will fall back to GSM !!

Since VoLTE is already announced on the Fairphone 3, please put in another weekend or so to port it to FP2, devs. Please…

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Easy, man. The shutdown of 3G for O2 will occur by the end of 2021:

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But what’s the point? You are now calling over GSM and you will do later too, so it would be nice to have the possibilty to use VoLTE, but it’s not necessary.

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I think it is 3G UMTS, not 2G GSM.

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No, 3G is used for data, GSM for calling and SMS, so nothing changes.

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Eh, no. 3G supports voice calls without a data carrier:


This article explains why phone calls were not possible in a 4G net, before VoLTE.

From the article:

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Yes, without VoLTE the handset has to use 3G or 2G.

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That is exactly what I have meant when I wrote

As far as I know, O2 serves 2G and 3G. A mobile handset capable of using 3G will probably prefer it as well due to better quality for voice calls.

O2 serves 2G and 3G and 4G, the latter including VoLTE. O2 has announced the availabiliy of “VoLTE for everybody”. And the FP2 does contain a VoLTE module, but it seems to simply lack the IMS data, which O2 (Telefonica) and Fairphone will have to put together (Telefonica disclosing the data, and Fairphone distributing it. AFAIK that is part of the (proprietary) modem driver in the phone’s firmware.

I can see the VoLTE module in my FPOS (just enter star hash star hash 4636 hash star hash star in the dialler and you can see it), but it’s grayed out and cannot be activated.

As far as I know at the moment, a higher data rate doesn’t help, because calling via 2G or 3G is not packet based. So the only backdraw is, that a data transfer via 4G will be stopped, when a phone call is made, instead of switched back to 3G speed.

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I could live with THAT. I’m not in the habit to simultaneously stream multimedia content WHILE making a call :slight_smile: I simply want to be able to continue using my FP2.

And GSM is the predecessor of 3G, so after 3G is shut down, the clock is ticking on 2G…