
Glossary
162
S
SAS Satellite Access Station. The gateway between the satellites and
the worldwide networks such as Internet, telephone network,
cellular network etc.
SDU Service Data Unit. Also known as a data packet.
SIM Subscriber Identity Module.The SIM provides secure storing of the
key identifying a mobile phone service subscriber but also
subscription information, preferences and storage of text
messages.
SMS Short Messaging Service
Streaming A technique for transferring data - such as audio or video clips -
so that it is processed as a continuous stream. With a Streaming
connection you are charged by the minute, like for a telephone
connection.
U
UDI Unrestricted Digital Information
UMTS Universal Mobile Telecommunications System. One of the third-
generation (3G) cell phone technologies, standardized by the
3GPP.
V
VPN Virtual Private Network. A network that is constructed by using
public wires to connect nodes. You can create networks using the
Internet for transporting data, using security mechanisms so that
only authorized users can access the network.