Walid,
It shold work for outgoing, though I think you may have other problems that you have not considered.
How can you limit the incoming calls to each tennant? The carrier will not have the same channel segragation that you are trying to use, and so will allow the incoming calls of one tenant to swamp the channels of the others.
The service provider may not let you specify the channel outgoing and may do channel negotiation, which means they may force the router to make the call on a different channel (of a different tennant) and so not follow what you want to achieve. This is all dependant on the protocol.
Most managed services do not specify a number of channels, more that channels are available and then bill on useage which is far easier to do. That way channel segragation is not needed.
Paul
