Does SFOS actually support 5G on the Xperia 10 III at all or is this a Nimitz Class aircraft carrier sized elephant in the room that nobody dares to ask about on this forum? 
According to my quick testing (and a few other answers on the forum) the answer seems to be no 
I have no clue how much work it requires on top of VoLTE…
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I have to admit I like mixing my metaphors as much as the next guy, but in this forum I don’t think people mince words when it comes to these questions.
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Funny thing, I’ve spotted that particular aircraft carrier sized elephant in the forums these past few days. Funny how no one mentioned it before…. ::smh::
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I wonder why nobody at Jolla cared to inform us over all these months that 5G may not be available on a 5G phone after you install SFOS.
I can’t find any official statement about missing 5G anywhere. I guess it’s apparently just such an insignificant feature nobody would care about it anyway, to the point it was not even worth mentioning it at all, while they write about such essential things like some cameras not being supported, etc.
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Opened a post about it here: Xperia 10 III support - #159 by cyberlyra. Interested to see the response.
Hm, I put my T-Mobile SIM into the 10 iii with stock Android 12, and my network scanner reported I was successfully on 4G VoLTE. Should I have expected differently, or be testing something else?
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You should be able to test if the phone is really sing VoLTE if the connection is not dropping to 3G when you’re making a voice call. Plus mobile data should be still working while you’re in a call.
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Cool. Now volte needs to roll out to more devices.
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Thank you. I don’t think if the importance of this find can be overstated. There have been multiple threads going on for months speculating about this very topic.
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Just because a given phone has VoLTE service with stock doesn’t mean it will with a custom ROM.
Take the case of the Xperia 10+. Android 10 resulted in VoLTE working. Lineage indicated it was working on the banner and engineering menus but would drop to 3g/2g when a call was actually in progress. Sailfish didn’t use VoLTE at all.
You are 100% sure that it is fully functional and not dropping to 3g/2g while a call is in progress?
Jolla didn’t mention 5G at all, the talk was always explicitly about VoLTE. However, as X10III has 5G capabilities, one would assume… Well, y’all know what they say about assuming 
It would have been nice/cool, but as 3G is dying (fast), VoLTE sure must have the priority over 5G. (Okay, some areas are packed with 4G traffic, so in some cases 5G could actually be highly beneficial. Ask me why I know…)
I’m sure 5G will sorted out at some point!
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Reporting on my experience, three days in with SFOS running on Xperia 10iii in USA:
- 4G indicated throughout the call
- No drops to 3G or 2G during or after calls
- No dropping off networks between calls (this happened repeatedly to me on 10 and 10ii)
- When 4G is active I can access websites during calls
- Stronger and more consistent signal than 10ii, 10, and XA2
I tested with Android 11 before flashing SFOS with same results.
Note that a bug has been reported about Beta VoLTE dropping after toggling wifi; discussion of workarounds is here. It occurs regardless of country or carrier, so likely not due to a mismatch with US networks.
Edit: Works on both TMobile prepaid and postpaid accounts.
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Ahm … the irony is it never mentioned 5G, so how do you come up to the conclusion that it supports 5G?
This is like if I am not mentioning a Mercedes but talk about VW you conclude I have Mercedes 
My experience with Jolla 4.4 on Xperia 10 III on ATT: there is no data link. no LTE / 4G period. The upper right shows 3G but the IP network is not reachable even on 3G.
3G calls are solid in and out. (apparently ATT still has a local tower serving 3G). but no data over SIM. The same Xperia 10III works solid with Android (both 11 and 12) and the same SIM/
Also noticed, that Connectivity – Cellular Network doesn’t have the following fields: to input MMSC value,
MCC and
MNC value
and APN type
and APN protocol
those fields are a must in order to have LTE working under Android. If I set to Choose networks manually, than I have an option to at least select the MNC (in my area can be 410 or 260) but There is still no place to type APN ( it should be: default, mms, supl, hipra,fota ) and APN protocol (Should be Dual) , and APN Roaming protocol (should be just IPV4).
next - will try to buy t-mobile SIM and of course will wait for Jolla 4.5 version to come and fix all the above. +))
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Thanks for sharing this, @nemirova . I was hoping AT&T would give the 10 iii 5G functionality but I guess not. :-/
Update: AT&T just told me the phone was incompatible with their network. No signal on Android and can’t register on the network with Sailfish. YMMV.
Get a Tello sim. It’s cheap and they are on t-mobile network.
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