Internal Program Version: SpanDSP  3.0.0

SpanDSP is a library of DSP functions for telephony, in the
8000 sample per second world of E1s, T1s, and higher order
PCM channels. It contains low level functions, such as
basic filters. It also contains higher level functions,
such as cadenced supervisory tone detection, and a
complete software FAX machine.

http://www.soft-switch.org