Is the source code of
chat program (used for dialog with modem) open? If it is so, where can I find it? I've been trying find it, but no success.
How to find it yourself next time:
Find the package containing the command. On Debian and its derivatives e.g.
dpkg -S /full/path/to/chat` or `apt-file search bin/chat`
If necessary, find a more detailed description of the program, e.g.
apt-cache show ppp
Feed your favourite search engine with homepage [packagename | Description]