Install iaxmodem by entering the following commands in the terminal:
sudo apt update sudo apt install iaxmodem
Description:
software modem with IAX2 connectivity
IAXmodem is a software modem written in C that uses an IAX channel (commonly provided by an Asterisk PBX system) instead of a traditional phone line and uses a DSP library instead of DSP hardware chipsets. . IAXmodem was originally conceived to function as a fax modem usable with HylaFAX, and it does that well. However IAXmodem also has been known to function with mgetty+sendfax and efax.
Homepage: http://iaxmodem.sourceforge.net/
Version: 1.2.0~dfsg-3
Section: universe/comm