the invention relates to a multimode communication terminal comprising a first modulation / demodulation circuit adapted to communicate with a first radio access network and at least a second modulation / demodulation circuit adapted to communicate with a second radio access network different from the first radio network . the terminal according to the invention comprises a synchronization module provided with means for determining a frequency difference between the first modulation / demodulation circuit and the first radio access network and means for synchronizing the second modulation / demodulation circuit with the second radio access network so as to allow said terminal to compare permanently transmission qualities over the first and second radio access networks .