Inter asterisk exchange, lovingly called iax (pronounced: eeks), is the protocol used by the asterisk pbx system for inter-asterisk-communication. other applications may use libiax to communicate with each other and other asterisk servers. iax is a high performance, feature rich protocol unrelated to sip or h.323. its single-socket design allows it to interoperate with nat and pat masquerade firewalls. it supports internationalization, remote dialplans, and voice, html, image, dtmf, and video content.