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How to limit calls to SIP trunks

I have a customer who's interested in purchasing and using SIP trunks to a service provider.

Consider that this customer has a MPLS network, and they are currently the built in CUCM locations based (hub and spoke) call admission control.

Since all locations (including the HQ location) is considered a spoke to the MPLS network, each location is defined in CUCM as a location.  Also since the SIP trunk they are considering purchasing is NOT from the same provider (as the MPLS network), the SIP trunk provider will drop off an Ethernet connection into their HQ location... I think will "break" the built in locations based CAC function in CUCM if I setup the SIP trunk as a seperate location within CUCM.

All calls from HQ locations AND from remote office will use this SIP trunk.

Assuming we use a CUBE gateway, what is the best way to limit the number of calls to/from the SIP trunk provider.

I've found two different commands that I think will do the job..

1.  Use the max-conn command under the voip dial-peer that points to the SIP trunk provider on the CUBE gateway.

2.  Use the call-treatment/threshold command on the CUBE router.

Does anybody have a recommendation on which one to use?  Is using one method better than using the other method?



You can limit the number of call on CUBE by using the following methods

• Limiting calls per dial peer: This simple call-counting mechanism controls the maximum number of simultaneous calls entering the enterprise network.

• Limiting calls based on memory and CPU used at the Cisco Unified Border Element: This overload protection mechanism helps ensure your network is not overrun with a burst of unmanageable call traffic.

Good info!  Are the methods you listed below turned on using the commands I asked about in the original question?

Also, do each of these methods provide a message back to CUCM such that CUCM will hunt to the next entry in the route-list?

Example, say I have two CUBE gateways each with a SIP trunk to a seperate provider.  On CUCM, I create a route-list that points to CUBE1 as a primary and CUBE2 as a secondary.  Do you know if the message sent back to CUCM (from CUBE1 when CUBE1 is "maxed-out") is similar to "NoCircuit/Channel available"?  If so, then CUCM will be able to follow the second entry in the route list.  (See


Hi there,

When you say, "I think will "break" the built in locations based CAC function in CUCM if I setup the SIP trunk as a seperate location within CUCM." why is that?

If the SIP trunks from the provider don't have a maximum number of concurrent calls (or if you don't need to worry about setting that limitation because that's the job of the SP itself) you could configure the trunks in either the default hub location or set up another location with unlimited bandwidth. At the end of the day, the limit in the number of calls placed will usually be more tight in your branches than in the central location.

If, however, you do have a maximum number of calls you can place through those trunks, just configure the location parameter to that value in CUCM. That, from my point of view, will always be easier than adding a CUBE and tuning the configuration.

Maybe I'm missing something here, if so, please let me know and I'll be happy to suggest some other workarounds.



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