Why is CUCM reporting phone registration rejected?

[luis.rosello]

Hi Peeps,

I'm running a 12.0 cluster, and using solarwinds to monitor it.  We constantly get "alerts" for phone registration rejected.  I've argued with management to disable this useless alert, but they believe it to be valid.  So I'm trying to figure out why we're getting them.  Phones get replaced and moved around constantly, so I would expected to see these messages. 

In any case, here's the questions I have:

What causes CUCM to reject phone registrations?

Is this part of a new phone deployement process?

Can I pinpoint the device in RTMT or logs?  How?  (Need to find culprit!)

Why don't these get cleared when the phone registers successfuly?

This is the MIB in question:

ccmRejectedPhones OBJECT-TYPE
-- 1.3.6.1.4.1.9.9.156.1.5.7.0
-- iso(1). org(3). dod(6). internet(1). private(4). enterprises(1). cisco(9). ciscoMgmt(9). ciscoCcmMIB(156). ciscoCcmMIBObjects(1). ccmGlobalInfo(5). ccmRejectedPhones(7). 0
SYNTAX Counter
ACCESS read-only
DESCRIPTION
"The number of phones whose registration requests were rejected by the local call manager."

[Jonathan Schulenberg]

Common reasons for a registration rejection that users wouldn’t notice would be unplugging the old phone before deleting it or changing the MAC during a swap or choosing the wrong model when creating one.
You would need to pull SDL traces from the cluster and know how to read them. A TAC engineer could help you understand it for the first time - it’s not easy to just rattle off in a quick forum post. There is a reason code in the log that will explain why CUCM rejected it.

[luis.rosello]

Thanx, I'll open a TAC case then to see if we can get to the actual reasons for the rejections.

[VoIP Engineer]

Are you re-using old phones that were connected to a previous cluster?  They could have bad certs / trust list.

Are people configuring their own IP Communicators?

You'll get a rejection if you configure a device as the wrong model (i.e. build a 7941 as an 8841)

[luis.rosello]

Hi Mr. Mason,

These are MACD from the same cluster, so I wouldn't expect bad certs or any other issues of that sort.  It does seem new, out of the box phones sometimes get rejected first, of course when I check CUCM, they are registered and working properly...