The call path verification feature in VRC is used to trace a call in a Voice-over-IP (VoIP) H.323 network. The call is traced from the originating gateway, through all gatekeepers used to resolve the destination address, and finally to the terminating gateway.
Note: You can only use VRC call path verification if prefix routing information is available on the network's gatekeepers and directory gatekeepers. We recommend that you not use call path verification if you are using carrier sensitive routing (CSR) and the CSR routing engine is providing the route information.
Note: Routes identified with target ipv4.* or dns.* are reported but not traced or verified by VRC.
To trace the call path using VRC you must enter the following information:
Call source - Choose the ingress gateway, or the voice port or trunk group for the ingress gateway.
DNIS - The number received from the Public Switched Telephone Network (PSTN).
Target Carrier - Select from the list of target carriers defined in the Administrative Domain (AD). This is not required if the CSR route type of the AD is set to None (for prefix routing only).
The translation profiles applied during call path verification are determined by the source of the call path verification request.
The call source is the device from which the call is traced. It is always a gateway, but you can provide more details by selecting the trunk group or the voice port through which the call was received.
Select the interface for which translation rules are defined so that the translation rules can be applied to the called number.
Do not define the translations for both trunk groups and voice ports. With this configuration, the router executes the voice port rules and ignores the trunk group rules. VRC does not have enough information to tie voice port rules with trunk group rules and cannot determine which rules to apply.
If there are no translation rules defined on voice ports or trunk groups, and you are using carrier-based routing, select the trunk group. The source carrier determined by the trunk group has a direct affect on the call routing.
The DNIS is the number received from PSTN by the originating gateway. It can contain the technology prefix, if it is present in the original number.
You cannot configure a target carrier on the originating gateway, but it can be added to the call path by the routing server if your system is configured to use one.
VRC cannot contact the route server to query for the target carrier information for the given entry parameters (source carrier, time of day, current traffic patterns).
However, you can presume the target carrier that the routing server would select under the current conditions. VRC verifies that all devices in the path are correctly configured to route and terminate the call. If the routing server would return, as a result of a query, the terminating gateway (thus shortening the routing path and not requiring the correct gatekeeper configuration), the system configured by VRC should have all gatekeeper connectivity in place.
Note: The target carrier setting is optional. If you leave this field blank, you test the behavior of the system with the routing server down or not used.
The following translation rules are executed to trace a call path:
Voice port translation rules (only if you select a voice port)
Trunk group translation rules (only if you select a trunk group)
You receive a warning if there are voice port rules defined.
Ingress gateway number expansions
Ingress route inbound translation rules
Ingress route outbound translation rules
Egress gateway number expansions
Egress gateway VoIP translation rules
Note: VRC call path verification does not recognize voice source groups, their translation rules, or ingress route call blocking.
After applying all ingress translation rules, the resulting called number (without associated technology prefixes), is matched against the list of zone prefixes for all zones that are accessible from the ingress gatekeeper or directory gatekeeper.
If a technology prefix is part of the called number, either as part of the original DNIS, or added by the gateway (this can be set in the ingress route), it is matched against the list of hopoff zones that are accessible from the ingress gatekeeper or directory gatekeeper.
When the egress gatekeeper is selected, all provided data is used to select the gateway that meets the given criteria (the prefix, tech prefix and target carrier). Gatekeepers select the terminating gateway based on the static prefix priority list (by default every gateway registered in the zone can accept the call), dynamically registered tech prefix, and dynamically registered list of trunk groups and carriers.
Every gateway that meets the specified criteria is included in the call path verification, but only the gateways with at least one egress route that matches target carrier and/or destination pattern successfully terminates the call and only those paths are listed as confirmed successful paths. The other paths are reported with the error message that indicates the call setup is initiated by the originating gateway, but it fails because of an improper configuration on the terminating gateway.
Note: VRC does not validate non-dial plan parameters such as codec or DTMF-relay between the call endpoints.