The GPRS Mobility Management determines if the user equipment is registered to the network or not. In another words, it defines if the network knows about the presence of the user equipment or not.  

In addition, if the user equipment is registered to the network, to which extent the network can determine the location of the user equipment. If it is to the cell level, or only to the routing area level.

2G Mobility Management (MM states)

There are three MM states for a user equipment in 2G network. Those states are,

• IDLE
• STANDBY
• READY

IDLE state

• In Mobility Management (MM) IDLE state, the network didn't register the user equipment.
• Therefore, the network doesn’t know about the presence of the user equipment.

STANDBY state

• In Mobility Management (MM) STANDBY state, the network registered the user equipment.
• Therefore, the network knows the location of the user equipment.
• However, the network knows the user equipment location only to the routing area level, it doesn't know which cell under this routing area the user equipment is currently using.

READY state

• In Mobility Management (MM) READY state, the network registered the user equipment. Therefore, the network knows the location of the user equipment.
• In addition, the network knows this location to the most accurate level, which is the cell level.

3G Mobility Management states (PMM states)

The Mobility Management states in 3G network are named the 'PMM states'.

There are three PMM states of a user equipment accessing the network through 3G network. Those states are,

• PMM-DETACHED
• PMM-IDLE
• PMM-CONNECTED

PMM-DETACHED state

• In PMM-DETACHED state, the network didn't register the user equipment.
• Therefore, the network doesn’t know about the presence of the user equipment.

PMM-IDLE state

• In PMM-IDLE state, the network registered the user equipment.
• Therefore, the network knows the location of the user equipment.
• However, the network knows the location only to the routing area level, it doesn't know which cell under this routing area the user equipment is currently using.

PMM-CONNECTED state

• In PMM-CONNECTED state, the network registered the user equipment.
• Therefore, the network knows the location of the user equipment. In addition, the network knows this location to the most accurate level, which is the cell level.