MSRN - Mobile Subscriber Roaming Number
The Mobile Subscriber Roaming Number (MSRN) is a temporarily telephone number assigned to a mobile station which roams into another numbering area. (This is usually another country). This number is needed by the home network to forward incoming calls for the mobile station to the network it visits. It is stored in the Home Location Register (HLR).
This number can be assigned by the visited network upon initial registration, or it can be assigned on a per call basis. In the latter case the number has to be requested by the home network (HLR) for each incoming call before it can forward the call to the visiting network.