A network infrastructure device of an apparatus in one example comprises a first external interface and a second external interface. The network infrastructure device communicates with a first telecommunication network through the first external interface. The network infrastructure device communicates with a second telecommunication network through the second external interface. The network infrastructure device allows a mobile communication device that has a first registration in the first telecommunication network and a second registration in the second telecommunication network to receive, through the second telecommunication network, a call directed to the first registration. The first telecommunication network is unable to directly query the second telecommunication network for a status of the second registration.