A mobile device capable of communicating on multiple radio access networks simultaneously may concurrently operate calls of a first call type on a first network and a second call type on the second network. As the mobile device approaches the limits of the service area of the second network it may take measurements to result in the call of the second call type to be serviced by the serving cell of the first network which is serving the mobile device for the first call type. In this manner the mobile device may ensure that when it leaves the service area of the second network, the calls of the first call type and second call type are served by the same serving cell in the first network.