slackbuilds_ponce/libraries/gsm

gsm contains command line utilities and libgsm, an implementation
of the European GSM 06.10 provisional standard for full-rate speech
transcoding, prI-ETS 300 036, which uses RPE/LTP (residual pulse
excitation/long term prediction) coding at 13 kbit/s.

The homepage link is dead there is no known homepage at this time.