Off topic'ish billing question

Hi all

Perhaps this is a bit off topic, so my apologies.

I am researching into doing some real time billing "type" work within
kannel for SMS.  Now, the environment is an OPSC from orga systems.  I
have very limited docs at the moment but I have stumbled across
something called real time IN-billing, which seems like some form of low
level socket interface. It looks promising but lack of info is a
problem.

I am wondering if anyone out there has any info on this sort of thing,
or can point my in any useful direction, and thereby speed up my
research work.

Tia

mike