Install isdnvboxserver by entering the following commands in the terminal:
sudo apt update sudo apt install isdnvboxserver
Description:
ISDN utilities - answering machine server
Let your Debian system be your answering machine! Messages can be accessed remotely, automatically emailed, etc. . This package provides the vbox server, which must be installed on the system with the ISDN card. To actually listen to the recorded messages you need the client package (isdnvboxclient) somewhere, not necessarily on the same system.
Homepage: https://www.isdn4linux.de
Version: 1:3.25+dfsg1-9ubuntu2
Section: universe/utils