This is a theoretical question is for a college assignment. I want to connect international IP inbound calls to a router in building A, this router will be connected to 4 PSTN E1's (Europe) going to a PABX in building B, that host the ACD and distributes the calls to the contact center agents. Now, if the 120 DS0's (4 E1's) are in use and a new international IP inbound call arrives to the router in building A, he will not find a voice circuit to route the call to the PABX in building B, so it should send a busy tone to the caller. What I'm trying to see is, if the router in building A can place this new call in queue until a PSTN 64 kbps DS0 channel (from the 4 E1's) is available, routing this call through this channel to the PABX in building B in order to reach an agent, and how it should be configured. Hope my question is clearer. Thanks, Kike.