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Problems with incorrect Vlan assigned to Cisco 7941

We have a network that contains Cisco 7941 Cisco IP Phones that have been working fine.

We are now begining to experience problems with phones getting IP addresses from the data vlan rather than the voice vlan?

We had a Call Manger upgrade in December but no other changes since the problem is intermitent but constant.

There was a similar post a whil ago where the solution was to change the swith port mode from access to trunk.

Don't understand why this would have worked and the post did not fully explian.

Any suggestions, help would be really appreciated as this issue is ongoing with no end in site.

If the original contributors have further information re their solution would be gratefull for their input.



Did you ever figure this out?  I'm trying to get 7941's to work on the voice vlan through a Cisco Small Business switch--2024p--and so far they only get their IPs from the data vlan.  Thought maybe your fix might help...if you found one.  Our voice system is a Cisco UC520.  Thx in advance....~Paul

Since its not supported its not a 'problem'  :=)


To answer your switchport access/trunking question, switchport access will allow one vlan to be used on the port; trunking will allow more than one vlan to be used on the port. 

Alternative solution:  I had the same vlan issue with a 7941 on our network.  I also found that POE was not working.  The resolution in our case was to replace the patch cable from the wall jack to the phone.  It was apparently faulty.

Frequent Contributor


I would want to know which Cisco Small Business Switch you guys are using. If it’s the older SRW switches then you have to manually set 802.1Q trunk settings on both the switch and the phones. If it’s the newer SRW (SG300/SF300) then make sure you’re on the latest firmware and the switch has been factory reset. Since they have introduced CDP on these switches it will automatically detect voice traffic via CDP in proper voice vlan. Our UC team here supports (SBSC) the UC540/UC560 guessing they work similar as the UC520. Since the new code is introduced CDP into the newer SRW SG/SF switches now they support auto-voice vlan

Hope this helps,



can i  add that I have trouble actually connecting with 3905 telephony switches sf 300 48p POE. I found the latest firmwares of the switch and the phone. only this model takes the data vlan and not register normally   at all / but7962 , 7931 phone on works fine on the seam port  .can somune  add for it .

sharon .

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