Glossary

S

SBC
Session border controller: a VoIP device that controls call admission to a  network and performs a number of call-control functions to ease the load on the call agents within the network.
SDH
Synchronous digital hierarchy
SDK
Software development kit
SDR
Software defined radio
SDSL
Symmetric digital subscriber line
SDU
Service data unit
Second life
An online society within a 3D world and almost three million residents.
SGSN
Serving GPRS support node: mobile packet data element within a GPRS network that handles GTP tunnels and forwards them to gateway GPRS support nodes (see GGSN).
Shadow consumer
The in-game avatar.
SIP
Session initiation protocol: a text-based OSI application layer protocol. Widely recognised as the protocol for all IP-based media sessions.
SLA
Service level agreement
SLC
Subscriber loop carrier
SME
Small or medium-sized enterprise
SMS
Short messaging service
SN
Service node
SNMP
Signalling/simple network management protocol
Soft client
Visual software client for telecoms services
Softswitch
Telecoms switching equipment combining the functionalities of PSTN switches and next-generation packaged switches, typically with routing intelligence separated from the physical interface unit to allow a more cost-efficient deployment of several switches within the same network. Also known as a call agent, media gateway controller, or media gateway, a softswitch can support ATM, DSL, Frame Relay and IP.
Sonet
Synchronous optical network
SOX
Sarbanes-Oxley Act: US legislation concerned with ensuring financial transparency that affects any company with a listing on a US Exchange.
Special access service
A transmission path connecting an interexchange carrier location in a Lata directly to an end user premise or another interexchange carrier location.
Spit
Spam over internet telephony
SPOI
Signalling point of interconnection: demarcation point on a SS7 signalling link.
SS7
Signalling System Number 7
Street cabinet
An outdoor cabinet that provides protection for fibre management functions: splicing, patching and passive component integration.
Supernode
Used to describe a user’s computer in a peer-to-peer network that acts as a relay between one user and another.
Switch
General term to mean an ACD, PBX or telephone exchange.
Switched access service
The transport of switched traffic between end-users and carriers. Switched access connects end-users to interexchange carriers (IXCs), mobile network operators (MNOs) and competitive local exchange carriers (CLECs).