Ip phone not getting registered

[umeshplamthottam]

Hi everyone, 

Our few ip phones are not getting registered on CUCM, it's a seperate office. Intermittently the phones are getting registered after a reebot. After a while it will unregistered from the server.

Can any one please suggest me some troubleshooting.

CUCM have reachability to the ip range which getting for the phones. 

[Nithin Eluvathingal]

Since its a separate office, i assume there could be a firewall in between the phones and CUCM. if yes, Did you check the firewall ?

2.12.0.0

[umeshplamthottam]

Hi Nithin,

Yes this is a seperate office but the phones are registering after reboot and after few minutes it's gets unregistered. I don't know what is exactly shown on phone screen at that time.

Until we give an explanation for why it is registering after reboot we can't involve any other team like network or security into this issue.

Concerned POC is asking for an explanation on this intermittent phone registration.

Also the phone is getting ip. From cucm I can access it's information page but no debug messages are uploaded. 

There only showing tftp time out and keep alive timeout. 

[Nithin Eluvathingal]

Since you face this issue just with a branch office phones, i don't think it as a phone issue or something related to IPT.

You need to check this from network/security level.

2.12.0.0

[umeshplamthottam]

Thanks Nithin the phones are registering at some time also we don't have
any voice v lan configuration on the site

[umeshplamthottam]

Hi Nithin,

Now the phones are registered we don't know how long it will stay in registered state with server. Also security team confirms that there is a firewall in between CUCM and the office.

Can you guide me what to check on firewall side.