Editing Cellular network (section)

== Broadcast messages and paging ==
Practically every cellular system has some kind of broadcast mechanism. This can be used directly for distributing information to multiple mobiles. Commonly, for example in [[mobile telephony]] systems, the most important use of broadcast information is to set up channels for one-to-one communication between the mobile transceiver and the base station. This is called ''paging''. The three different paging procedures generally adopted are sequential, parallel and selective paging.

The details of the process of paging vary somewhat from network to network, but normally we know a limited number of cells where the phone is located (this group of cells is called a Location Area in the [[GSM]] or [[UMTS]] system, or Routing Area if a data packet session is involved; in [[3GPP Long Term Evolution|LTE]], cells are grouped into Tracking Areas). Paging takes place by sending the broadcast message to all of those cells. Paging messages can be used for information transfer. This happens in [[paging (telecommunications)|pagers]], in [[CDMA]] systems for sending [[Short message service|SMS]] messages, and in the [[UMTS]] system where it allows for low downlink latency in packet-based connections.

In LTE/4G, the Paging procedure is initiated by the MME when data packets need to be delivered to the UE.

Paging types supported by the MME are:

* Basic.
* SGs_CS and SGs_PS.
* QCI_1 through QCI_9.