We have a weird situation when we receive a call via PSTN caller does not hear initially..Then we hear a busy tone and once we drop the call. We get ringback again and we connect and could continue the conversation. We have folloing setup..
CM (4.1.3)---H323--Cisco 2851--PSTN (ISDN PRI). We are running 12.4.12 on the 2851 router.. Any clue would be helpfull..
Check to see if you have a dial-peer with direct-inward-dial statement (for onestage incoming dialing)
Under dialpeers, sometimes it helps to put the "NO VAD" statement. VAD sometimes causes pauses for incoming calls.
It turned out to be a QoS misconfiguration for the signalling traffic, which was causing the call setup issues.. It is fixed now.. Thanks any ways..