An Interworking Location Register (ILR) is a register used at the outside of a GSM network for inter-standard roaming when the mobile networks use different signalling protocols. An ILR performs, amongst other things, the following functions:

An ILR is e.g. needed for roaming between GSM and AMPS.

The subscriber will need an mobile phone for each of the technologies or a dual mode mobile telephone.

See also