• Handoff (or handover) is a control process initiated when a mobile moves from its current cell to its neighboring cell.

• A user of a mobile phone will be moving continuously. In such a situation, the mobile connection should also remain intact especially if the user is currently using the phone.

• This transfer of connection from one cell to another should be quick and in such a manner that user doesn’t actually realize that a handoff has happened.

• There are four basic types of handoffs in GSM network:

1. Intra-cell handover

Such a kind of handover is performed to optimize the traffic load in the cell or to improve quality of a connection by changing carrier frequency.

2 Inter-cell handover

It is also known as Intra-BSC handover.

Here the mobile moves from one cell to another but remains within the same BSC (Base station controller).

Here the BSC handles the handover process

3 Inter-BSC handover

It is also called as Intra-MSC handover.

As BSC can control only a limited number of cells, we might usually need to transfer a mobile from one BSC to another BSC.

Here the MSC handles the handover process.

4 Inter-MSC handover

It occurs when a mobile moves from one MSC region to another MSC.

MSC cover a large area. It can be imagined as a handover from Maharashtra MSC to Gujarat MSC while travelling.