Hmm.
Possible US work around:
T-mobile has the Digits app which allows multiple phone numbers, likely with sip.
I wonder if anyone has tried to call with it. Obviously it requires Alien Dalvik.
With all the restrictions Jolla puts on Alien Dalvik though, for instance blocking mms/sms access for Android apps, which is a pain, I wouldn’t be surprised if it doesn’t work…is worth a try though.
Just heard that /e/ plans to support VoLTE. I hope that Jolla will do the same. If it is true that telecom is going to end 2G and 3G ,how can we make calls with a Sailfish device?
sigh…
/e/ is android (its a fork of lineageos). yes its true 2g/3g are ending in many (most) places, some very soon or already happened, and you cannot make calls with a sailfish device if your telecom shuts down both 2g and 3g. (your service will be largely degraded if 3g service is shutdown, even if 2g remains)
Thanks. One little comment: /e/ is a de-googled fork of lineageos
As far as possible, they say.The functionality is very good, at least on a GigasetGS290, but not as beautiful as Sailfish and no local apps.
Regarding /e/ : you’ll get basically the same setup in Aliendalvik if you install the opensource microG instead of the official proprietary Google Play Service.
Absolutely. The business world still relies heavily on voice calls, and incoming calls are invariably voice. As far as using Google Fi, Google Voice, Facebook Messenger, and Whatsapp…you’re not seriously recommending that security minded invididuals who take the time to install adb, unlock the bootloader on a handset, flash that handset, and discusses related issues on here should or would actually want to use any of those services, do you?
I’m afraid you’re barking up the wrong tree. 
I’m one of the anti-big-tech Taliban on this forum.
btw, restarting ofono is sufficient to get the android data link working for me when it gets disconnected. ymmv, of course, might be a different, similar bug. anyway, i have a button binding to restart ofono when i click camera button 4x quickly. it takes about 4s from clicking to establishing LTE link in google maps
Can’t we just have an app in the AD that routes the 3G connection to 4G datalink? Grab the interface for 3G and pipe it to the Android side?
Maybe applying this fix to the base AOSP from the installer zip might fix it… It’s worth a shot.
note that i said restart ofono, not android. have you tried this? it is sufficient for me.
(note that restarting ofono is something that can be done without interrupting most functionality, and takes only seconds).
in fact, i have another (separate) problem with ofono already on 3G with tmobile, and i restart ofono every 10 minutes (with timeD, after checking if the phone is locked and no voice call is happening).
while far from perfect, you could do what i do and then you would be unlikely to miss calls in an android app.
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if you can write a script that checks if android has internet, you could run it every 60s fairly safely
I’d love if you could share a guide on how to do it. I am not scared of the terminal or of editing config files, but I have no idea how to bind actions to repeated button presses.
IMHO, it’s no use manually enabling VoLTE, since Sailfish middleware doesn’t support it. VoLTE is basically SIP, and since Sailfish doesn’t support that either natively… All we can do is wait… 
Or develope the patch and push it. But those parts are closed source and available to licencees only, I guess?
my script for monitoring button input sf-button-monitor:
thread for sf-button-monitor
https://talk.maemo.org/showthread.php?p=1570143#post1570143
where i configure timed commands/etc:
network-fix in sx-config is what i use to restart ofono automatically when the screen is locked
P.S.: if you want to have sfbm work reliably with the screen turned off, you need to run it with keepalive-tool. i do this 100% of the time on my x compact, and have noticed zero decrease in battery life.
In Switzerland, 2G is decomissioned already. 3G still works, but was announced to last until 2024. So I can use my SFOS phone until then at least. 3G coverage is okee but not great though and I encounter more and more corners, where I cannot do phone calls. VoLTE would really be a blessing…
In Android VoLTE protocolstack is implemented in LTE chips firmware or drivers. VoLTE uses seperated APN “ims” to connect IMS that handles VoLTE calls.
I think VoLTE is wrong question, correct one should be 5G and VoNR (5G version of VoLTE). 5G networks won’t support CSFB. So in 5G VoNR is must.
Nah. It’s mostly the same thing. And most, if not all 5G networks are co-deployed with 4G, so “first things first” only makes sense.
My point was that VoLTE support and 5G support is tied together. And next phone after Xperia 10 II probably is 5G phone.