Forcing hangup on zaptel channels


We are testing a lab system for a telesales organization. We are mounting a TDM400P card fully confugured with 4 fxo modules.

This is a very simple system and the only we want is to connect 4 analog lines to either 4 or less agents who use idefisk softphones.

It’s very easy to achieve a system with 4 lines for 4 agents but we are willing to provide a very specific feature. We want that if we have less than 4 available agents, i.e. 3 ones, then only three lines will remain “available”. We want that the othe ones will remain physically hanged up, so the caller won’t charged whit one call fare.

We don’t want to fake de busy situation playing “busy” tones, because doing this way caller will be charged for sure.

Any idea?