A few things that can cause the state to be rejected. First would be in the ATA has an old configuration file, since it is SIP it learns it's directory number via the configuration file, the SIP REGISTER sent to CUCM contains the directory number in the config file, so if the config is not up to date and the CUCM server has a different directory number than what the ATA is sending in the SIP register you will see the status as rejected. Next if you have changed any device pools (callmanager groups with in those device pools). If you have a call manager group set on the device in CUCM to contain servers B and C, but the configuration file contains server A and D, it will try and register to A and D but due to those servers not being in the call manager group set on CUCM, the registration attempt will be rejected. Lastly, if you enabled any type of encryption on your CUCM cluster this can happen. If you recently set the cluster to mixed mode or changed the security profile, you may want to run an install/update operation in the CAPF (Certificate Authority Proxy Function) from the device page in CUCM so the certificate the device presents to CUCM is up to date.
One other thought, since some are working fine and some are not, if you haven't made any changes that you are aware of check database replication. You can do this from the command line of the publisher with "utils dbreplication runtimestate" or from the web page using the Cisco Unified Reporting Tool. Also checking the Event Viewer - Application logs (alternate syslog files) will provide a good indication of the reason why the devices are not registering.
IntroductionCUCM Routing RulesDial String implementation PolicyCUCM Routing LogicSIP URI Call Routing Analysis+++ Case Study: 1 ++++++ Case Study: 2 +++Conclusion
Over the last few months, I have had the privilege of working on SI...
Are you getting this error “Installer User Interface Mode Not Supported. The installer cannot run in this UI mode. To specify the interface mode, use the -i command-line option, followed by the UI mode identifier. The value UI mode identifiers...