Techniques are disclosed relating to the communication between server systems located in different network regions. For example, in some embodiments, a first server system located in a first network region may receive a request to perform a first operation for a user, where the request includes an alias value for the user. The first server system may determine, based on the alias value, that the user is not associated with the first network region. In response, the first server system may access an alias map that specifies encoded versions of alias values that are in use across multiple different network regions and, using the alias map, determine that the user is associated with a second network region. The first server system may then route a communication corresponding to the request to a second server system that is located in the second network region.