The present invention provides a method of operating a paging controller in a wireless communication system including a first network that operates according to a first radio access technology and a second network that operates according to a second radio access technology. The first network includes a first control plane entity and the second network includes a second control plane entity. The method includes providing, to at least one first base station in the first network, a request to transmit a page to a first tracking area associated with the mobile unit. The first tracking area is defined in the first network. The method also includes providing, via an interface between the first control plane entity and the second control plane entity, a request to transmit the page to a second tracking area associated with the mobile unit. The second tracking area is defined in the second network.