Continuity Testing Call Flow (CCR/COT)

Continuity tests are used to test the speech or transmission path of SS7 circuits. It also make sure that the SS7 ISUP interface circuits (CIC) are aligned with the same physical links (E1/T1) on both end equipments. Toolpack version 2.7 allows users of the TMG to do ISUP Continuity Testing via 3 methods by CIC Group or individual CIC:

Incoming Continuity Testing Outside A Call

This circuit testing occurs when one of the nodes wants to validate a currently idle circuit. It is recommended that the switch first blocks the circuit to prevent calls to use the circuit during the testing.

For ITU:

         Peer SP                     TMG
           |                          |
           |---------- CCR ---------->|        
           |                          | (timeslot loopback)
           |---------- Tone ----------\
           |<-------------------------/
           |                          |
           |---------- REL ---------->|
           |<--------- RLC -----------|

For ANSI:

         Peer SP                     TMG
           |                          |
           |---------- CCR ---------->|
           |                          | (timeslot loopback)
           |<--------- LPA -----------|
           |                          | 
           |---------- Tone ----------\
           |<-------------------------/
           |                          |
           |---------- REL ---------->|
           |<--------- RLC -----------|

Incoming Continuity Testing Within A Call

This circuit testing occurs when the forward side (originating side) sets the ‘continuity test required’ field of the ‘nature of connection indicators’ IE into the IAM message.

Successful continuity check:

         Peer SP                     TMG
           |                          |
           |---------- IAM ---------->| 'continuity test required'
           |                          |
           |                          | (timeslot loopback)
           |---------- Tone ----------\
           |<-------------------------/
           |                          |
           |---------- COT ---------->| continuity check successful
           .                          .
           .                          . 
           .                          .
           |---------- REL ---------->|
           |<--------- RLC -----------|

Failed continuity check with retry from Peer SP:

         Peer SP                     TMG
           |                          |
           |---------- IAM ---------->| 'continuity test required'
           |                          |
           |                          | (timeslot loopback)
           |---------- Tone ----------\
           |<-------------------------/
           |                          |
           |---------- COT ---------->| continuity check failed
           |                          |
     Retry |---------- CCR ---------->|        
           |                          | (timeslot loopback)
           |---------- Tone ----------\
           |<-------------------------/
           |                          |
           |---------- COT ---------->| continuity check successful
           .                          .
           .                          .
           .                          .
           |---------- REL ---------->|
           |<--------- RLC -----------|

Outgoing Continuity Testing

Users of the TMG unit can generate out of call SS7 ISUP Continuity Tests via webportal easily.

         Peer SP                     TMG
           |                          |
           |<--------- CCR ---------- |        
(timeslot  |                          |
 loopback) |                          |
           /---------- Tone ----------|
           \------------------------->| ccr success or fail
           |                          |
           |<--------- REL -----------|
           |---------- RLC ---------->|

Configuration

• Web Portal v2.7: Outgoing Continuity Testing

External Sources

• Q.784-ISUP BASIC CALL TEST SPECIFICATION