A method performed by an interworking system comprising: (a) receiving, from a visited network having a first wireless network infrastructure type that employs Diameter signaling protocol, a first update location request message according to Diameter signaling protocol, the first update location request message originating from a mobility management entity, MME, at the visited network and associated with a user equipment roaming at the visited network; (b) assigning a serving general packet radio service, GPRS, support node, SGSN, global title, GT, to the MME from a pool of GTs for MMEs associated with the visited network and converting the first update location request message to a second update location request message according to mobile application part, MAP, signaling protocol; (c) transmitting the second update location request message to a home network associated with the user equipment, the home network having a second wireless network infrastructure type that employs MAP signaling protocol; (d) receiving, from the home network, an update location response message according to MAP signaling protocol, the update location response message including a user profile associated with the second wireless network infrastructure type; (e) generating a combined user profile based on a user profile associated with the first wireless network infrastructure type and the user profile associated with the second wireless network infrastructure type; and (f) transmitting the combined user profile to the visited network in an update location answer message according to Diameter signaling protocol using the MME address which corresponds to the SGSN GT assigned. (a) receiving, from a visited network having a first wireless network infrastructure type that employs Diameter signaling protocol, a first update location request message according to Diameter signaling protocol, the first update location request message originating from a mobility management entity, MME, at the visited network and associated with a user equipment roaming at the visited network; (b) assigning a serving general packet radio service, GPRS, support node, SGSN, global title, GT, to the MME from a pool of GTs for MMEs associated with the visited network and converting the first update location request message to a second update location request message according to mobile application part, MAP, signaling protocol; (c) transmitting the second update location request message to a home network associated with the user equipment, the home network having a second wireless network infrastructure type that employs MAP signaling protocol; (d) receiving, from the home network, an update location response message according to MAP signaling protocol, the update location response message including a user profile associated with the second wireless network infrastructure type; (e) generating a combined user profile based on a user profile associated with the first wireless network infrastructure type and the user profile associated with the second wireless network infrastructure type; and (f) transmitting the combined user profile to the visited network in an update location answer message according to Diameter signaling protocol using the MME address which corresponds to the SGSN GT assigned.