A method and apparatus for transferring between radio access networks deployed under different radio access technologies is described. A wireless transmission / reception unit is equipped with at least two radio units to support different radio access technologies. Each radio access network sends a list of radio access networks located in the coverage area of the radio access network to the wireless transmission / reception unit. The wireless transmission / reception unit stores the list and determines if one of the co-located radio access networks meets the transfer criteria. Then, the wireless transmission / reception unit initiates a transfer from a current radial access network to a target radio access network if the latter satisfies the transfer criteria. Otherwise, the wireless transmission / reception unit may send a measurement report to the current radio access network, whereby the latter determines whether one of the radio access network selected between the access networks of Co-located radio satisfies the transfer criteria to start the latter towards the selected radio access network.