Editing Network switching subsystem (section)

{{Short description|Component of the Global System for Mobile Communications (GSM)}}
{{Use American English|date = March 2019}}
{{multiple issues|
{{no footnotes|date=March 2019}}
{{Refimprove|date=March 2009}}}}
'''Network switching subsystem'''  ('''NSS''') (or '''GSM core network''') is the component of a [[GSM]] system that carries out [[telephone exchange|call out]] and [[mobility management]] functions for [[mobile phones]] [[roaming]] on the [[Base Station subsystem|network of base stations]]. It is owned and deployed by [[mobile phone operator]]s and allows mobile devices to communicate with each other and [[telephone]]s in the wider [[public switched telephone network]] (PSTN). The architecture contains specific features and functions which are needed because the phones are not fixed in one location.

The NSS originally consisted of the circuit-switched [[core network]], used for traditional [[GSM services]] such as voice calls, [[Short message service|SMS]], and [[Circuit Switched Data|circuit switched data]] calls. It was extended with an overlay architecture to provide packet-switched data services known as the [[GPRS core network]]. This allows mobile phones to have access to services such as [[Wireless Application Protocol|WAP]], [[Multimedia Messaging Service|MMS]] and the [[Internet]].