I have a Galaxy S3 mini (running 4.4.2). I configured my SIP account in the corresponding part of the settings, I told Android to accept incoming calls over SIP, it is properly registered. I then told Android to use SIP calls (it calls it "Internet calls", apparently) whenever I have a wifi connection.
This seems to work OK: if I'm connected over wifi I can make phone calls even without a SIM card.
But now "Messages" doesn't seem to obey those settings: if I don't have a SIM card, and I try to send a text message, it just tells me "No signal found for mobile networks". How can I tell "Messages" to use SIP when I'm connected over wifi?
Alternatively, I see in contacts that I can add an IM address, so I figured maybe I could add SIP address in there (would be less convenient since I'd have to remember whether to send over SMS or over SIP), but SIP does not appear among the supported protocols in that field (it does include many protocols, tho, including Skype, Jabber, Hangouts, AIM, Yahoo, ICQ, and then some). How can I add a SIP address in there?