Editing Cellular network (section)

=== Cellular handover in mobile phone networks ===
{{Main|Handover}}
As the phone user moves from one cell area to another cell while a call is in progress, the mobile station will search for a new channel to attach to in order not to drop the call.  Once a new channel is found, the network will command the mobile unit to switch to the new channel and at the same time switch the call onto the new channel.

With [[CDMA]], multiple CDMA handsets share a specific radio channel. The signals are separated by using a [[pseudorandom noise|pseudonoise]] code (PN code) that is specific to each phone. As the user moves from one cell to another, the handset sets up radio links with multiple cell sites (or sectors of the same site) simultaneously. This is known as "soft handoff" because, unlike with traditional [[cellular technology]], there is no one defined point where the phone switches to the new cell.

In [[IS-95]] inter-frequency handovers and older analog systems such as [[Nordic Mobile Telephone|NMT]] it will typically be impossible to test the target channel directly while communicating. In this case, other techniques have to be used <!--how does NMT handover work exactly?? --> such as pilot beacons in IS-95. This means that there is almost always a brief break in the communication while searching for the new channel followed by the risk of an unexpected return to the old channel.

If there is no ongoing communication or the communication can be interrupted, it is possible for the mobile unit to spontaneously move from one cell to another and then notify the base station with the strongest signal.