Editing UMTS (section)

== Migrating from GSM/GPRS to UMTS ==
From a GSM/GPRS network, the following network elements can be reused:
* [[Home Location Register]] (HLR)
* [[Visitor Location Register]] (VLR)
* Equipment Identity Register (EIR)
* [[Mobile Switching Center]] (MSC)
* [[Gateway Mobile Switching Center]] (GMSC)
* [[Authentication Center]] (AUC)
* Serving GPRS Support Node ([[SGSN]])
* Gateway GPRS Support Node ([[GGSN]])

From a GSM/GPRS communication radio network, the following elements cannot be reused:
* Base transceiver station (BTS)
* Base station controller (BSC)
* Packet Control Unit (PCU)
They can remain in the network and be used in dual network operation where 2G and 3G networks co-exist while network migration and new 3G terminals become available for use in the network.

The UMTS network introduces new network elements that function as specified by 3GPP:
* [[Node B]] (base transceiver station)
* [[Radio Network Controller]] (RNC)
* Media Gateway (MGW)

The functionality of MSC changes when going to UMTS. In a GSM system the MSC handles all the circuit switched operations like connecting A- and B-subscriber through the network. In UMTS the Media gateway (MGW) takes care of data transfer in circuit switched networks. MSC controls MGW operations.