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CUCM Routing Issue

Joshua Levine
Level 1
Level 1

CUCM 9.x

2 sites with a network link between them

Site1: Main site with call manager servers, unity server, and a gateway with a PRI with a dedicated DID # range

Site 2:  Gateway (with SRST) with a PRI with a dedicated DID # range 

DID # ranges do not overlap

Internal calls between the sites are normally routed over the network link.  If the network link fails, the system is programmed to automatically add the appropriate digits and send internal calls out via the PSTN (i.e. via the PRI's).


We would like to implement a feature offered by the Carrier providing our PRI's that automatically redirects calls to numbers on a failed PRI (or one with all channels busy) to another PRI (in this case the other site PRI). 

However, the feature would also be active in a failure scenario where both a PRI and the network link between sites is down. Incoming calls intended for the failed site PRI would automatically be directed by the Carrier feature to the other site's PRI, but since the link between sites is down, the system would automatically try to route the call back out via the PSTN to the failed site. It seems that a repeating loop might occur until all channels on the good PRI are busy, preventing any further inbound or outbound calls.

Is this reasoning correct?  Any suggestions on how to approach a solution would be appreciated.  Thanks.

3 Replies 3

Gordon Ross
Level 9
Level 9

My thought, would be to put the gateways in different CSSs to the phones.


The phone's CSS would contain route patterns that first try the network link, then the PSTN.

The gateway's CSS would contain a route pattern that only tried the network link.



Please rate all helpful posts.

Thanks. Have to think this though a bit though, since there are other considerations (not all technical) that have to be accounted for before experimenting/testing/implementing any significant changes in this active system.

Incidentally, the gateways with PRI's are H.323 controlled, not MGCP.

oops.....meant to say "think this through a bit though.......