Make and receive SIP calls on your iPhone with PBX or phone provider running SIP. Full DTMF, mute, hold, call history, and STUN/ICE without extra hardware
PulseSIP turns your iPhone into a full-featured SIP desk phone — no dedicated hardware required. Connect to any standard SIP server, Asterisk PBX, or hosted VoIP provider and start making calls in minutes.

PulseSIP is Open Source software licensed under GPL v2. Source code is available at Github:
https://github.com/pulsely/PulseSIP/