How to check if service is available???

My call listener is starting with phone, and it initialises itselfs before user insert pin code. It initialises Rline and other stuffs... When call occures it is still working but goes crazy .

The problem is that the line isn't valid when it connets to it.  After pin inserting line is activated, but my call listener uses still old invalid service...

Anybody knows solution?

How to check if line is connected to service?

Time delay isnt good idea in this case....

Regards
Wojtek