with all the VoLTE / VoWifi / WifiCall talk, I was missing a SIP howto. If you have great connectivity but no voice service into or from the classical phone network it’s good to have an alternative.
The built in client is bare bones, audio codecs are what you’re used to from 3g networks. But it works! is lightweight! has your contacts already!
To get an SIP account, use voip.ms or callcentric in the US and enter details. If you want to rely on the service, please read their E911 page how emergency service is routed (to the address of your registration mostly) and how text messages work(*).
(*) voip.ms has text messaging since mid 2020. I haven’t tested if the /e/ messages app (qksms) can use the sip account to text. If not, there is a separate app: https://f-droid.org/packages/net.kourlas.voipms_sms/
The components the AOSP Dialer SIP implementation is built upon is on its way out by Android 12, Google is doing nothing there anymore.
Opensource SIP Clients that can do more interesting codecs (think “HD Voice” - Speex/Opus) and transport encryption, look to Linphone. The excellent “Conversations” as app can do SIP too, though does it via xmpp (jmp.chat for example).
Closed source Apps with adjacent commercial sevice and probably easy registration and setup flow are Zoiper and Viber.
I am having trouble since a few month with the build in SIP client (using it with two numbers). Not sure / investigated what the problem is: Client, LOS, SIP provider or the openwrt router.
Sad to hear about Google phasing out support, read more about it here
Tor, the underlying tech for the AP hide-my-ip feature, doesn’t carry UDP, it’s TCP only [^1]
and in a common config you’ll use UDP for the RTP part (audio stream) of VoIP, as datagrams are a better fit for voice communication (latency more important than every packet delivered).
Some SIP parts are TCP, but not the voice stream. I think there exist TCP based audio communication, WebRTC can do it as fallback if I’m not mistaken, but not the classic SIP/RTP VoIP stack by my current knowledge.
So anyway, disable the Tor part in Advanced Privacy if you use this kind of IP based telephony.
[1] (there are spec proposals for tunneled UDP over TCP though).
