I have asterisk 1.6 running on Ubuntu 12.0. Asterisk is connected to gsm gateway via sip. Recently, they offered here in Lebanon premium numbers. These numbers cost a lot of money to call. The problem is that they have no certain pattern or range and I do not want asterisk to call these numbers. When asterisk dial a premium number, an ivr message alert about the rate cost and give the option to hangup at no charge before it start ringing, so there was no answer during the ivr. So I want asterisk to hangup when it hears the ivr.