Abstract: The present invention provides a message sending method and a serving GPRS support node. The method includes: when the SGSN, to which user equipment is connected, switches from a first SGSN to a second SGSN, the first SGSN sending to the second SGSN a message carrying context information of the user equipment, wherein the context information includes the gateway type of packet data network to which the user equipment is connected. The present invention achieves the effects that the new SGSN can acquire the gateway type of the packet data network PDN and correctly select the type of the interface in use according to the gateway type.