
La señalización número 7 es la señalización de canal común más ampliamente usada en telecomunicaciones entre nodos de conmutación telefónica internacional y está normatizada por la ITU.
http://www.cnc.gov.ar/numeracion/zip/T-REC-Q.705-1993-03.pdf
What about SS7?
The SS7 architecture consists of the following signaling points (as shown in ):
•Service Switching Points (SSPs) are telephone switches equipped with SS7 software and signaling links. Each SSP is connected to both STPs in a mated pair.
•Signaling Transfer Points (STPs) receive and route incoming signaling messages toward their destinations. STPs are deployed in mated pairs and share the traffic between them.
•System Control Points (SCPs) are databases that provide the necessary information for special call processing and routing, including 800 and 900 call services, credit card calls, local number portability, cellular roaming services, and advanced call center applications.
http://www.cisco.com/en/US/docs/routers/access/as5300/software/notes/6011.html#wp3732
What is ISDN?


http://www.techfest.com/networking/wan/isdn.htm