The 4-Port OC-48/STM-4 Channelized/Unchannelized ATM Service Module is a line card. This ATM switch service module has four physical 2.5Gbps interfaces that can be used to deliver high-density OC-48 or STM-16 trunking and User-Network Interface (UNI) or aggregation of sub-OC-48 traffic through port channelization.The 4-Port OC-48/STM-4 Channelized/Unchannelized ATM Service Module can reside in the Cisco MGX Multiservice Switch to provide support for up to 48 OC-48/STM-16 interfaces for service providers that require both high bandwidth and high network availability.The 4-Port OC-48/STM-4 Channelized/Unchannelized ATM Service Module meets service providers' demand for carrier-class availability by offering hot-standby 1+1 card redundancy as well as port redundancy with SONET/SDH automatic protection switching (APS).