flexfax: How to get the costs of a fax?

[Szomraky Stefan <stevewonder2@gmx.net>]

I want to set up a fax server, but the clients should not be allowed to
send millons of faxes, and surely the should not fax to Japan.

Thus I need to know how many the telephon company will bill me for the faxes
sent by a specific user. (and how many faxes he sent).

Additionally specific numbers should be locked (emergrency call, etc.).

Are there any programms for that? Or is there a way to collect informations
about it to let a (own written) program calculate it?

Thanks!