zlacker

>>quenti+(OP)
Tangential, but to 1.: Isn't RCS just built upon TCP/IP and SIP? Why can't you just implement it in user space? Or does it need to send some magic packets through the modem? It is really hard to find details on the protocol.

>>captai+I7
Another problem is that Google's RCS implementation has a Signal-protocol prekeys-exchange server in the loop that is not accessible for the public. So even if you'd implement RCS you could not send messages to android devices as you can't fetch the prekeys through anything but the Messages app.