Welltech Dialogic SS7 Protocols ISUP Manuel d'utilisateur télécharger pdf (Page 104)

Section 6 Interface to Application

Unsuccessful continuity test call

The continuity test is initiated as in the previous example. If the continuity

check is unsuccessful, a Continuity request is sent indicating failure and timer

T26 (waiting for sending CCR on subsequent COT failure) should be started

by the application. The transceiver should be removed at this point. On

expiry of this timer, the continuity test should be re-initiated on the same

circuit by sending a Circuit seized request, applying the transceiver, and

starting timer T24 (waiting for sending COT on receipt of backward check

tone).

Removing and re-applying the transceiver (rather than leaving it in place

whilst waiting to perform the continuity re-check) avoids the possibility that

the continuity check may continually fail due to the fact that the transceiver

was not correctly applied initially.

Figure 20. Example of a Continuity Check Request Message Sent (Unsuccessful

Continuity Check Followed By Successful Continuity Check)

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SZE CCR

SZE

REL REL

RLC RLC

CCR

COT (failure)

COT (success)

ISUP

MODULE

USER

APPLICATION

NETWORK

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Welltech Dialogic SS7 Protocols ISUP Manuel d'utilisateur Page 104