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Cisco IP Telephony Troubleshooting Guide for Cisco CallManager Release 3.0(1)
The disconnect cause values (origCause_value and destCause_value — depending on which side
hung up the call), map to Q.931 disconnect cause codes (in decimal) that can be found at
http://www.cisco.com/univercd/cc/td/doc/product/software/ios113ed/dbook/disdn.htm. In the
example above, cause 16 refers to a normal call clearing. If the call is going out a gateway to the
PSTN, then the CDR can be used to determine which side is hanging up the call. Much of the
same information can be obtained by enabling tracing on the Cisco CallManager. Use the trace
tool only as a last resort or if the network is not yet in production.
Check Your Loads
As with any problem, check the phone and gateway loads and CCO (Cisco Connection Online at
www.cisco.com) for the latest software loads, new patches, or release notes relating to the
problem.
Cisco CallManager Feature Issues
Problems may occur with features that are used in conjunction with Cisco CallManager, such as
Conference Bridge or Media Termination Point. Some feature problems can be caused by
configuration errors or lack of resources. For example, users may not be able to conference calls
if the specified number of Ad Hoc conference resources has been exceeded. The result would be
a dropped call when the user attempted to initiate the conference feature. This could appear to be
a Cisco CallManager feature issue, when in fact it is a problem with the number of available
conference resources. The number of times a conference resource was required but not available
is one of the counters logged in Microsoft Performance. The same behavior would occur if there
are conference resources available, but the conferencing service had stopped.
Codec/Regions: Codec Mismatch
If a user gets a reorder tone when going off-hook, it could be the result of codec disagreement
between regions. Verify that both call ends support at least one common codec (for example,
G.711). If not, you will need to use transcoders.
A region specifies the range of supported codecs that can be used with each of the other regions.
Every device belongs to a region.
Note: Codec negotiation with a Cisco IOS router is not supported.
For example, Region1<->Region2 = G.711, means that a call between a device in Region1 and a
device in Region2 can use G.711 or any other supported codec that requires the same or less
bandwidth as G.711 (any supported codecs within G.711, G.729, G.723, and so on).
Note: The following codecs are supported for each device:
Cisco IP Phone 7960 — G.711A-law/µ-law, G.729AnnexB
Cisco IP Phone SP12 series and VIP 30 — G.711A-law/µ-law, G.723.1
Cisco Access Gateway DE30 and DT-24+ — G.711A-law/µ-law, G.723.1
© 2000 Cisco Systems, Inc.
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