Introduction to SS7 – Part 2 Konrad Hammel Sangoma Technologies

ITU –14 bits, format or decimal ANSI –24 bits, format SPC –Self Point Code APC –Adjacent Point Code DPC –Destination Point Code OPC –Originating Point Code Node Addressing 2

Sample of using SPC, APC and DPC 3

Sample using OPC and DPC 4

Decimal = 1234 Hex = 0x4d2 Binary = = Converting Point Codes 5

SS7 Stack layers 6 MTP1 MTP2 MTP3 ISUP SCCP Physical Data Link Network Presentation Transport Session Application TCAP MAP/INAP

Call Signaling protocol of SS7 Controls the status of CICs –Resets, blocks, etc Controls the call setup –Setup, acknowledge, hang-up, etc CICs –Circuit Identification Code –Integer number that uniquely identifies a time slot on a span –Used by all messages to id the specific channel ITU Q.762, Q.763. and Q.764 ANSI (T1.113-YEAR) ISUP 7

Basic Call Messages IAM –Initial Address Message –Call request ACM –Address Complete Message –Acknowledges IAM –Starts early media ANM –Answer Message –Answers the call REL – Release – Request to hang-up a call RLC – Release Complete – Acknowledges a REL 8

Basic Call Flow 9

SAM –Subsequent Address Message –Sends additional call setup info (overlap) CPG –Call Progress Message –Used to signal additional info during call setup –Really only used for Supplementary Services CON –Connect Message –Can replace ACM+ANM Advanced Call Messages 10

Advanced Call Flow 11

Circuit Control Messages RSC –Reset Circuit Message –Resets a single circuit to idle state –Acknowledged with RLC BLO –Circuit Blocking Message –Single circuit is put into maintenance block –Receiving side can not make calls on circuit BLA –Blocking Acknowledge Message –Acknowledges reception of BLO UBL – Circuit Unblock Message – Removes a previous maintenance block UBA – Circuit Unblock Acknowledge Message – Acknowledges reception of UBL 12

Circuit Group Control Messages GRS –Circuit Group Reset –Resets a range of circuits –Max range is 31 GRA –Circuit Group Reset Acknowledge –Acks a GRS CGB – Circuit Group Block – Blocks a range of circuits – Maintenance or Hardware block CGBA – Circuit Group Block Acknowledge CGU – Circuit Group Unblock CGUA Circuit Group Unblock Ack 13

Continuity Message A test to confirm that a CIC is working properly from end to end The requested CIC is looped, an audio/test pattern is transmitted on the channel. If the pattern is not successfully received then the test fails. Used to confirm continuity of the network COT/CCR 14

THANK YOU. 15