A method of operating a mobile communications network, the method comprising the steps performed by an apparatus (122, 300) of the network: a) in response to a mobile terminal losing a first connection with a first network base station (112a, 112b, 112c) and then making a second connection with a second network base station determining a network search parameter value for the mobile terminal, wherein the network search parameter value represents a period with which the mobile terminal will perform periodic searches for its home mobile network; b) transmitting the network search parameter value to the mobile terminal; c) periodically re-determining the value of the network search parameter if the mobile terminal is still connected to the second base station; and d) transmitting the network search parameter value determined in step c) to the mobile terminal; wherein: i) the first network base station comprises a femtocell (110a, 110b, 110c) associated with the home mobile network; ii) the second network base station comprises a macrocell associated with a visited mobile network; iii) the area covered by the macrocell comprises a plurality of femtocells (110a, 110b, 110c) located therein; and iv) the value of the network search parameter is determined in accordance with the state of the home mobile network such that the determined value of the network search parameter decreases as the probability that the femtocell associated with the home mobile network is available to the mobile terminal increases; the method further comprising: determining that a failure of the home mobile network has occurred; and inferring the probability that the femtocell associated with the home mobile network is available to the mobile terminal based on the time since the failure. a) in response to a mobile terminal losing a first connection with a first network base station (112a, 112b, 112c) and then making a second connection with a second network base station determining a network search parameter value for the mobile terminal, wherein the network search parameter value represents a period with which the mobile terminal will perform periodic searches for its home mobile network; b) transmitting the network search parameter value to the mobile terminal; c) periodically re-determining the value of the network search parameter if the mobile terminal is still connected to the second base station; and d) transmitting the network search parameter value determined in step c) to the mobile terminal; i) the first network base station comprises a femtocell (110a, 110b, 110c) associated with the home mobile network; ii) the second network base station comprises a macrocell associated with a visited mobile network; iii) the area covered by the macrocell comprises a plurality of femtocells (110a, 110b, 110c) located therein; and iv) the value of the network search parameter is determined in accordance with the state of the home mobile network such that the determined value of the network search parameter decreases as the probability that the femtocell associated with the home mobile network is available to the mobile terminal increases; determining that a failure of the home mobile network has occurred; and inferring the probability that the femtocell associated with the home mobile network is available to the mobile terminal based on the time since the failure.