Signalling System No. 7 - Wikipedia
https://en.wikipedia.org/wiki/Signalling_System_No._7
The SS7 protocol stack may be partially mapped to the OSI Model of a packetized digital protocol stack. OSI layers 1 to 3 are provided by the Message Transfer Part (MTP) and the Signalling Connection Control Part (SCCP) of the SS7 protocol (together referred to as the Network Service Part (NSP)); for circuit related signaling, such as the BT IUP, Telephone User Part (TUP), or the ISDN User Part(ISUP), the User Part provides layer 7. Currently there are no protocol compone… Status: In force Latest version: (03/93), March 1993 Year started: 1984
Status: In force
Latest version: (03/93), March 1993
Year started: 1984
DA: 70 PA: 19 MOZ Rank: 92