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Preconditions Interworking
The
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provides a preconditions support feature to reserve network resources as a preventative measure to minimize chances of session failure due to lack of resources before alerting the called party. This prevents a "ghost ring" where the called party is alerted before the call is set up.
This feature supports ISUP-SIP and SIP-SIP preconditions inter-working, and provides transparency by dropping/adding of preconditions attributes between supporting or non-supporting peers. The preconditions are configured from the
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at the SIP Trunk Group level using the parameters “preconditions” (for incoming requests) and “transmitPreconditions” (for outgoing requests).
The CLI syntax is shown below:
% set addressContext <addressContext_name> zone <zone_name> sipTrunkGroup <sipTrunkGroup_name> services preconditions [none | required | supported]
% set addressContext <addressContext_name> zone <zone_name> sipTrunkGroup <sipTrunkGroup_name> services transmitPreconditions [none | required | supported]
Preconditions Interworking Using 183 Response
The
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also provides preconditions support for 183 responses using following CLI syntax, (This flag is for specific call flows and is not intended for generic use)
% set addressContext <addressContext_name> zone <zone_name> sipTrunkGroup <sipTrunkGroup_name> services preconditionIntwkUsing183 <disable|enable>
Do not enable preConditionIntwkUsing183
when End-to-End Prack is configured.