FreeSWITCH is a Software Defined Telecom Stack enabling the digital transformation from proprietary telecom switches to a versatile software implementation that runs on any commodity hardware. From…

Sofia-SIP is an open-source SIP User-Agent library, compliant with the IETF RFC3261 specification.

SpanDSP is a low-level signal processing library that modulates and demodulates signals commonly used in telephony, such as the "noise" generated by a fax modem or DTMF touchpad.

C library implementing STIR-shaken STI-SP AS/VS, STI-CA