Belle-sip is a SIP (RFC3261) implementation written in C, with an object oriented API. * RFC3261 compliant implementation of SIP parser, writer, transactions and dialog layers * HTTP client API * support of client TLS certificate * fully asynchronous transport layer (UDP, TCP, TLS) * fully asynchronous DNS resolution with SRV * full dual-stack IPv6 support * SIP transaction state machines with latest corrections (RFC6026) * automatic management of request refreshes with network disconnection resiliency thanks to the "refresher" object * supported platforms: Linux, Mac OSX, Windows XP+, iOS, Android, Blackberry 10 WWW: https://www.linphone.org/technical-corner/belle-sip.html