Install isdnlog by entering the following commands in the terminal:
sudo apt update sudo apt install isdnlog
Description:
ISDN utilities - connection logger
This package provides a set of utilities that can log ISDN connections and calculate the cost of calls. If sufficient data is available, it can even recommend which alternate carrier would have been cheaper for a given call. For countries where calls are charged per discrete unit, it can disconnect the line just before the next unit starts.
Homepage: https://www.isdn4linux.de
Version: 1:3.25+dfsg1-9ubuntu2
Section: universe/utils