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50% of 7965G phones won't register at a certain building

Hello all,

So we have a publisher and 2 subscriber running CUCM 11.5.  All of my 7965 in other buildings works fine except this one particular building.  The weird thing is some of the phone work fines but after it loses power it doesn't work anymore.  I notice it's not pulling the correct load from TFTP either which is SCCP45.9-4-2SR3-1S.  If I take the phone from this building and bring it to my building it boots up just fine.  Our network team said its not network because they can ping and see the MAC on the switch.

The phones in this building are configured the same way as other building using voice vlan from what I was told by our network team.  


Any help would be greatly appreciated as we have been tackling this issue for weeks!

Leo Laohoo
VIP Community Legend

@thoeun0412 wrote:

The weird thing is some of the phone work fines but after it loses power it doesn't work anymore. 

Is the phone getting the correct IP address? 

If yes, what happens if you put the IP address into a browser?

The phone get the correct IP address and when I put it in a browser I get "This site can't be reached"

Leo Laohoo
VIP Community Legend

How about those that work? Can you browse to their IP address?

Phones registered to the publisher I get the phone information.  Phone registered to the subscriber I get the same error as above.

Leo Laohoo
VIP Community Legend

That's weird.
Can you ping the phone (that's not working) from a different subnet? From the same subnet?

I can ping the phone from a different subnet and from the same subnet.

Leo Laohoo
VIP Community Legend

Could be duplicate IP address.
Cisco Employee

+ What do you see on the phone screen when they are not registered? 

+ Are you able to check the phone status messages on the phone ? Do you see any error in those messages like 'Timeout' etc. 



Some phone get stuck on Registering.  Some phone power cycle forever.


The status message says DNS Timeout.

Leo Laohoo
VIP Community Legend

@thoeun0412 wrote:

The status message says DNS Timeout.

DNS timeout?  What is the value assigned to DHCP Option 150?  Is it in the form of an IP address?

The value assigned to DHCP is Option 150 pointing to our TFTP IP address.

Are CUCM nodes represented by host names instead of IP address? You can cross check that in System-->Server list on the CUCM.

If that is the case, phones will need DNS server to resolve those  in order to register.Make sure the DNS server provided by the DHCP server to phones can resolve those Host name/FQDN.  


CUCM nodes are represented by host names.  I will have my network team check to see if the DNS server can resolve those names.  More to follow.

Leo Laohoo
VIP Community Legend

I would never recommend anyone use the host names of the CUCM server to populate DHCP Option 150.
The reason being is because the time it will take to resolve the host name. It may not be much but it can make a lot of difference if there is a slow (or congested) WAN link.
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