An integrated telephony service can provide users with a single phone number and a single handset for use as a cordless device at a stationary location and for use as a mobile device. Incoming calls can be routed to the handset at the stationary location over a landline network. If unanswered at the stationary location, the calls can be routed to the handset via a service delivery point of presence over a wireless network. For outgoing calls from the handset, a switch within the handset can select cordless device operation when the handset is within range of a landline base station unit connected to the landline network and the handset can function as a cordless device in cooperation with the landline base station. If the handset is not within range of the landline base station, the switch can select mobile device operation and the call can be placed over the wireless network with the handset functioning as a mobile device.