Packet data network – A network such as the Internet that provides data services.
Subscriber Identity Module – A piece of hardware that can be inserted into SIM slot of a user equipment, for the purpose of connecting to a mobile service provided by a mobile service provider. Usually a small plastic card with a circuit on it.
Public Land Mobile Network – It is also known as cellular network and is identified by a globally unique PLMN code.
A point of presence (PoP) is a demarcation point, access point, or physical location at which two or more networks or communication devices share a connection. Points of presence include routers, switches, servers, and other devices necessary for traffic to cross over networks.