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New Member

IP Phone Registeration Issus

Hi Guys,

I set up a lab and used to be working fine till yesterday. The problem is the all the phones (7961 & 7960) in one VLans can not be registered on the Call Manager, but the phones in other vlans are working fine. For the phones that can not register themselves on the call manager, they still can get ip address from the PUB,which is my DHCP server. for the PUB and SUB, Auto-regiter has been enabled and tftp on both servers is running as well. on the screen, I can see the phone are requesting the SEPMACadress.cnf.xm file, and on CUCM, the phones shown regitered.... Can anyone give me any hints about it? Thanks



Everyone's tags (2)

IP Phone Registeration Issus


What happens if you move a phone from the problem VLAN to a "known good" VLAN?

What happens if you move a phone from a "known good" VLAN to the problem VLAN?

What we for here is a definition of the fault domain.

Other things you can look at:

  • Check your DHCP scope to ensure the appropriate options are being sent to the phones
  • Check your layer 3 routing.
  • Check ICMP from the CUCM to the phone and/or the phone's default gateway interface
  • Run a network capture on the CUCM to see if you see packets coming from and going to the phone (

  • Enable Detail level tracing on the TFTP process. Use RTMT to review the trace file to see what (if anything) is happening with the TFTP server. Detail level should allow you to see client connections and requests to retrieve files.
  • Use a TFTP client to retrieve a file from the CUCM TFTP server (just to be sure that is working). You are in a lab environment, so put your PC/Mac/etc. in the voice VLAN and test that if it seems appropriate




Please rate helpful posts.

HTH -Bill (b) (t) @ucguerrilla

Please remember to rate helpful responses and identify

New Member

IP Phone Registeration Issus

Hi William,

Thanks for answering my question.

If I move the phone from the problem VLAN to the good VLAN, the phone will be registered on the Call Manager Properly with a DN.

And if I move another phone from the good VLAN to the problem VLAN, the phone will stuck at requesting the SEPXX.cnf.xm file screen...

I double checked the DHCP scope on the call manager for that VLAN, and from the phone I can see they all can get the proper IP, DHCP server, default gateway, active and standby call manager..

My guess is since the phone can get the IP, so the layer 3 routing is good??

I can ping both PUB and SUB on the default gateway as well but I have not checked the connectivity from CUCM to the phones.

I have not got the chance to capture the network traffic neither, will do it as your instruction and update here.  Thanks




IP Phone Registeration Issus


This sounds like OPTION 150 the TFTP server address is incorrect or missing on the scope for

the dodgy vlan.

Check the option on the DHCP scope foe the VLAN in question.



Regards, Alex. Please rate useful posts.
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