Abstract: A method for connecting a first device belonging to a first mobile communications network of the narrow band type to a second mobile communications network of the wide band type, the device implementing a protocol layer for communicating with a first plurality of mobile terminals according to a first mobile communications standard, including a modification of the first device by integration of a transposition layer in the protocol layer and being linked to the second communications network of the wide band type via a link of the Internet Protocol (IP) type.