A method of controlling call admission within a system comprising a plurality of media gateways (8, 9) interconnected by a packet switched backbone (5). The method comprises, at least one media gateway (8, 9), monitoring the level of congestion suffered by incoming packets to that gateway from each other media gateway over said backbone. Following receipt of a request for a media gateway (8, 9) to terminate a bearer extending over said backbone (5) from a peer media gateway, making a decision on the admissibility of that request based upon the previously monitored level of congestion suffered by incoming packets from that peer media gateway.