A suite of open-source tools and frameworks for creating SIP apps
VoIP/SIP SoftPhone (formerly known as jphonelite)
High performance, production quality STUN server and client library
Free, native Windows SIP softphone with HD audio, SRTP encryption
AT commands as input are sent to modem and responses given as output.
Web based system for Computer Assisted Telephone Interviewing (CATI)
Go to github.com/vlm/asn1c for the latest version.
Baresip is a modular SIP User-Agent with audio and video support
H.323 Gatekeeper for VoIP and videconferencing