The Juniper Networks CTP150 Circuit to Packet platform optionally includes a replaceable CTP150-IM-T1E1 interface module that can be paired with another module of the same type or a serial interface module. The four-port T1/E1 interface module supports individual cabling for each port. The CTP150 ports have T1/E1 ports for RJ-48 connectors. The software-selectable T1/E1 interfaces for the module are T1, E1, fractional T1, and fractional E1. CSU options, encoding, and encapsulation are also software-selectable. The module also includes an external clock reference port for an RJ-48 connector. It is compatible with the CTP150 product line.