Support for network routing selection

A database of pre-stored information is provided to support address resolution to determine addresses that can be used to control routing through a network such as call routing through a telephone network or e-mail routing. When address describing data is received from a terminal of the network, address resolution equipment determines an identifier of an intended destination based on the address describing data, if need be by combining it with the database. The result is used to control routing of data through the network. Furthermore, the address describing data is inspected for information items that applied to the intended destination but were by themselves insufficient to determine the identifier, without using other parts from the address describing data. When such an information item is found, a new record is added to the database of pre-stored address resolution information or an existing record is modified the new or modified record representing that information derived from said insufficient information part applies to the identifier that was determined to supply the address. The new or modified record is subsequently used resolve further address describing data to route other data.