The Digital T1/E1 Packet Voice Trunk Network Module provides a flexible and scalable T1/E1 voice solution for Cisco 2600 and 3600 series multiservice Modular Access routers and supports up to 60 voice channels in a single network module. A single packet voice trunk network module supports both on-premise and off-premise connections to both Private Branch Exchanges (PBXs) and Public Switched Telephone Networks (PSTNs). For enterprise branches and large businesses wishing to migrate to packet-based multiservice infrastructures, the Digital T1/E1 Packet Voice Trunk Network Module leverages investments in existing legacy telephony equipment and enables the deployment of new packet voice applications while reducing recurring telephony charges.The Digital T1/E1 Packet Voice Trunk Network Module provides an ideal migration path to a multiservice network. Customers can gradually shift voice traffic from traditional circuit-switched networks to a single infrastructure carrying data, voice and video over packet networks without replacing any legacy PBX and key communication system equipment. The Digital T1/E1 Packet Voice Trunk network module can also provide the gateway or portal to the PSTN for Cisco IP phones which can be used in conjunction with legacy equipment.The product comes with an integrated add/drop multiplexer.