Nortel Networks NN10029-111 manual Relationship between Telephony routing stages

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These routes include routes for private digit dial plans, routes to gateways, and telephony-style routing between SIP domains. Multiple lists can reuse the same routes in a route list.

•assign class of service (COS)

COS is basically used to block particular types of calls, such as international dialing or long-distance dialing. For example, telephones in an office lobby can be restricted to local and emergency calls only in a domain.

Figure 5, “Relationship between Telephony routing stages,” shows the relationship between the telephony routing stages provided by the SIP Application Module. If the COS value of the subscriber and subdomain route do not match, then the SIP Application Module checks the parent for routes with the same or higher COS value.

Figure 5 Relationship between Telephony routing stages

No subscriber

Foreign domain routing

Do database lookup

Failed

DNS A record*

*If the DNS A record fails, a 404 Error response is sent back to the originator.

Route lists The Telephony routing service is an enhancement to the Location Server on the SIP Application Module. This enhanced Location Server function has the ability to translate PSTN numbers into

NN10029-111 Standard MCP 1.1 FP1 (02.02) April 2003 Copyright © 2003, Nortel Networks