A short message service (SMS) over SGs solution comprising an SGs application part (SGsAP) gateway. The SGsAP gateway is positioned between a mobile management entity (MME) on a long term evolution (LTE) network and a short message service center (SMSC)/home location register (HLR) on a circuit-switched (CS) network to permit SMS messages to be passed between the two domains. The SGsAP gateway performs centralized routing to home public land mobile networks (HPLMN) on the circuit-switched (CS) domain. An SGs interface is used to route messages between an SGsAP gateway and a mobile management entity (MME) on a long term evolution (LTE) network. The inventive solution does not require CS networks to support an SGs interface. In accordance with the principles of the present invention, a mobile management entity (MME) need only maintain a single SCTP association to a SGsAP gateway.