Editing Signalling System No. 7 (section)

==Physical network==
SS7 separates signaling from the voice circuits. An SS7 network must be made up of SS7-capable equipment from end to end in order to provide its full functionality. The network can be made up of several link types (A, B, C, D, E, and F) and three signaling nodes – [[Service switching point|Service Switching Points]] (SSPs), [[Signal Transfer Point]]s (STPs), and [[Service Control Point]]s (SCPs). Each node is identified on the network by a number, a signaling point code. Extended services are provided by a database interface at the SCP level using the SS7 network.{{citation needed|date=December 2014}}

The links between nodes are full-duplex 56, 64, 1,536, or 1,984&nbsp;kbit/s graded communications channels. In Europe they are usually one (64&nbsp;kbit/s) or all (1,984&nbsp;kbit/s) [[timeslot]]s ([[DS0]]s) within an [[E-carrier|E1]] facility; in North America one (56 or 64&nbsp;kbit/s) or all (1,536&nbsp;kbit/s) timeslots ([[DS0A]]s or DS0s) within a [[T-carrier|T1]] facility. One or more signaling links can be connected to the same two endpoints that together form a signaling link set. Signaling links are added to link sets to increase the signaling capacity of the link set.{{citation needed|date=December 2014}}

In Europe, SS7 links normally are directly connected between switching exchanges using F-links. This direct connection is called ''associated signaling''. In North America, SS7 links are normally indirectly connected between switching exchanges using an intervening network of STPs (Signaling Transfer Points). This indirect connection is called ''quasi-associated signaling'', which reduces the number of SS7 links necessary to interconnect all switching exchanges and SCPs in an SS7 signaling network.<ref>{{cite web|url=https://www.itu.int/rec/T-REC-Q.700-199303-I/en/|title=ITU-T Recommendation Q.700, section 2.2.3|pages=4–5|date=1993-03-01}}</ref>

SS7 links at higher signaling capacity (1.536 and 1.984&nbsp;Mbit/s, simply referred to as the 1.5&nbsp;Mbit/s and 2.0&nbsp;Mbit/s rates) are called [[high-speed link]]s (HSL) in contrast to the low speed (56 and 64&nbsp;kbit/s) links. High-speed links are specified in ITU-T Recommendation Q.703 for the 1.5&nbsp;Mbit/s and 2.0&nbsp;Mbit/s rates, and ANSI Standard T1.111.3 for the 1.536&nbsp;Mbit/s rate.<ref name="Q.703"/> There are differences between the specifications for the 1.5&nbsp;Mbit/s rate. High-speed links utilize the entire bandwidth of a T1 (1.536&nbsp;Mbit/s) or E1 (1.984&nbsp;Mbit/s) transmission facility for the transport of SS7 signaling messages.<ref name="Q.703">{{cite web|url=https://www.itu.int/rec/T-REC-Q.703-199607-I/en/|title=ITU-T Recommendation Q.703, Annex A, ''Additions for a national option for high speed signaling links''|publisher=[[International Telecommunication Union]]|pages=81–86}}</ref>

[[SIGTRAN]] provides signaling using [[Stream Control Transmission Protocol|SCTP]] associations over the [[Internet Protocol]].<ref name=Russell/>{{rp|456}} The protocols for [[SIGTRAN]] are [[M2PA]], [[M2UA]], [[M3UA]] and [[Signaling Connection Control Part#Transport over IP Networks|SUA]].<ref>{{cite web|url=https://www.eetimes.com/understanding-the-sigtran-protocol-suite-a-tutorial/?_ga|title=Understanding the Sigtran Protocol Suite: A Tutorial {{!}} EE Times|website=EETimes|date=6 November 2003 |access-date=2016-06-30}}</ref>