Things to do when you encounter the "Host Not Found" message on your Cisco desk phone when trying to access the corporate directory or extension mobility.

“Host Not Found” when Accessing the Corporate Directory

The “host not found” is an error message that can be found when pressing the Services or Directories buttons, or accessing Extension Mobility from a Cisco desk phone using Cisco Unified Communications Manager. From my experience it can often be caused simply by an incorrect DNS record, but on some occasions  there may be another root cause. Phone services such as the the Corproate Directory and Extension mobility rely on HTTP or HTTPS, that are hosted by you Cisco Unified Call Manager’s Tomcat web server. I recently encountered this issue and these were some troubleshooting steps that helped me resolve the issue and I hope that one of these solutions will also help you.

Possible Solutions

If you are getting Host not found error then please find below of the steps to remove this error:-

  • If this is a DNS issue make sure the phones’ DHCP scope points to proper DNS server and the DNS records for the CUCM server are correct. In my case my switch supplied DNS on the dedicated Voice VLAN. My solution was correcting the DNS entry within my core switch config.
  • To fix a dns issue you can also change the hostname to it’s IP address on the Call Manager under System->Server within CUCM administration.
  • Go under CCMadmin page >System >Enterprise parameters. and modify the Phone URL values from hostname to IP and then check if you still have the issue. Reset the phone to ensure that it looks at retrieving this information again.
  • Check your Firewall and make sure that there are no settings that are blocking access.
  • Restart the Cisco Trust Verification Service.
  • Restarting the Cisco Tomcat service can correct the issue. (requires a small outage window)
  • The could be a certificate that has expired.  Log into the Call Manager’s OS Administration console and regenerate the self signed certificate on the cluster.
  • If the issue is isolated to one phone you may want to do a factory reset on that phone.

Factory reset on this phone by doing the following procedure :

  1. Power off and power on the phone while pressing #
  2. When you see the red LED lit on the MUTE key.
  3. Enter 123456789*0# to initiate factory reset. (before LEDs are lit as Orange)

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