ISUP

SS7 Message Signal Units carry user-part payloads over MTP. Level-2 framing wraps length, sequence/ACK bits, and SIO/SIF; Level-3 routing…

SS7 network layer providing routing labels (DPC/OPC/SLS), linkset/route management, and discrimination to user parts. It carries ISUP, SC…

ISDN user-network call control: SETUP, CALL PROCEEDING, ALERTING, CONNECT, DISCONNECT, RELEASE. Information elements carry bearer capabil…

Text-based signaling for creating and managing sessions. Methods (INVITE, ACK, BYE, REGISTER…) and response codes resemble HTTP; SDP bodi…

SIGTRAN MTP3 user adaptation over SCTP that carries ISUP/SCCP payloads with routing keys for IP-SS7 interconnect. ASPs and SGPs exchange …

Local Number Portability lets a subscriber keep an E.164 number when changing carriers. Originating switches query an NPDB (often via TCA…

Calling Name Delivery presents a display name for the calling party at the terminating set. Classic wireline dips query a CNAM/LIDB datab…

Toll-free / 8XX service translates a dialed toll-free number to a routing number or carrier via an SCP (SMS/800, RespOrg databases) over …

North American Advanced Intelligent Network defines detection points, triggers, and SCP transactions (often over TCAP) for number transla…