When the SMSC determines it needs to attempt to deliver a Short Message to its destination, it will send the SMS-PP APDU containing the text message, the "B-Party" (destination phone number) and other details to the Gateway MSC (GMSC) logical component on the SMSC. The GMSC, on receipt of this Short Message, needs to discover the location of the B-Party in order to be able to correctly deliver the text to the recipient (the term Gateway MSC, in this context, indicating an MSC that is obtaining routing information from the Home Location Register (HLR)). To do this, the GMSC invokes the MAP service package MAP_SEND_ROUTING_INFO_FOR_SM, which sends a sendRoutingInfoForSM (SRI-for-SM) MAP message to the destination number's HLR, requesting their present location. This SRI-for-SM message may be sent to an HLR in the same network as the SMSC, or via an interconnect to an HLR in a foreign PLMN, depending on which network the destination subscriber belongs to.