G-SMSC is Gateway SMS Center. It is a gateway between two different network systems to send the SMS (Short Message Service). This G-SMSC enable a CDMA or GSM mobile network operator can interoperability between mobile operator with different technology (GSM or CDMA). So with this G-SMSC, subscriber can send SMS to other mobile operator.

G-SMSC can deliver SMS directly to VLR, over SIGTRAN or MAP-SS7, without going through the SMSC. This architecture is adopted from server-client architecture that accepts TCP/IP connection from SMS application, and support standard protocol like SMPP, HTTP or XML over TCP/IP.