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cucm 8.0 location-based CAC question

Hello--I've got a client with a centralized CM 8.0 deployment, with 3 remote sites connected via MPLS. At the largest of the 3 sites, they intermittently get 'not enough BW' messages. There is no pattern and it happens only at that site. Bandwidth logs don't show excessive use. Does anyone have any ideas?

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Priyadarshini B.T
Cisco Employee

Hi Scott,

The audio and video quality can begin to degrade when too many active
calls exist on a link and the amount of bandwidth is oversubscribed.
Call admission control regulates audio and video quality by limiting the
number of calls that can be active on a particular link at the same
time. Call admission control does not guarantee a particular level of
audio or video quality on the link, but it does allow you to regulate
the amount of bandwidth that active calls on the link consume. 

Call admission control operates by rejecting a call for bandwidth and
policy reasons. When a call gets rejected due to call admission control,
the phone of the called party does not ring, and the caller receives a
busy tone. The caller also receives a message on their phone, such as
"Not enough bandwidth."

please do refer the link below, you will get complete details regarding CAC

and get back to me in case of any issues

Joseph Martini
Cisco Employee

Which bandwidth logs did you look at?  What codecs are calls expected to use to other locations that go over the LAN/WAN?  Based on the codecs used, what's your configured bandwidth for each location (configured on your locations in CUCM) and how many calls are expected to be placed or allowed at any one time?  One quick thing to check is that the local gateway (if the remote sites have them) are in the same location as the phones at the same site, that way there are no bandwidth deductions for calls to the local gateway.

I appreciate the responses.  So far, haven't been able to figure out where the bandwidth logs are...i'm messing with RTMT but at this point i have to set it to unlimited because it's a retail environment and they can't call at all.

g.729 between sites.  Gateways are local, but only things going out those are 911 (copper trunks).  There's a central SIP trunk (g.729 to PSTN) at the main location.  at this location, i set it to 1024k total bandwidth.  At the main location, it's set to 4096k at the head-end...

Any tips on pulling the records from RTMT?

Hi Scott,

next time when you get the message "not enough bandwidth" do collect call manager traces immediately after the issue

i will send you the link below which will give you the steps to collect cucm traces.

along with the calling, called number and the exact time stamp.

or if you want to receive alerts from RTMT, you can try the following

Marwan ALshawi

by the way if you have local voice gateway to the PSTN it is better to use AAR as a backup method when your CAC return no enough bandwidth


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