A method of discovering multi-mode mobile terminals (13) in a heterogeneous network environment, each multi-mode mobile terminal (13) having at least one interface for sending packet data to and/or receiving packet data from a home radio communication network (11) and a foreign radio communication network (12), said home radio communication network having a different access technology from said foreign radio communication network, each multi-mode mobile terminal (13) performing the steps of: (a) listening to said foreign radio communication network (12); (b) receiving and storing a foreign network indicator for indicating presence of said foreign radio communication network (12); and (c) transmitting said foreign network indicator to said home radio communication network (11); whereby said home radio communication network (11) may store a database comprising a mapping between a multi-mode mobile terminal identity, a home network indicator and a foreign network indicator, to facilitate interworking of said home and foreign radio communication networks.