Method and a mobile phone terminal enabling to merge telephony services over heterogeneous networks

A method to merge telephony services over a circuit switched network (3) and a packet switched data network (4), in a mobile phone terminal, comprises the steps of: - receiving communication events arriving via a circuit switched network (3), - receiving communication events arriving via a packet switched data network (4), - storing communication events into a shared memory, - and analyzing communication events arriving via the circuit switched network (3) and communication events arriving the via the packet switched data network (4), and then routing each communication event to a voice application, either directly or via said means for storing, in order to store it temporarily, so that all the events concerning a same call are synchronized when they are received by said voice application.