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Community Member

7921 Loading Problems

Hey guys,

OK we deployed two 7921 phones at our client, the client has the mobility controller and 2 lightweight AP's that are fully configured. Wireless works fine, the phones can get an IP but can't get their load information.

I compared the phone boot to a functioning phone we have at our office. The issue I see is when the phone loads it goes through its process and then gets to 'Opening'

This is the firewall at the client which is a sonicwall.

At our office it says 'Opening' which is the UC500 IP.

My question is where do I change that setting? I have scoured the mobility controller and I can't find anything relating to that IP...maybe it is an easier fix through CLI. Any suggestions would be greatly appreciated.



Community Member

Re: 7921 Loading Problems

OK I resolved this one on my own. If anyone else runs into this problem here is the fix:

When using Windows DHCP scope you have to create a new scop option:

Open Dhcp manager, right click on the dhcp server and select "set predefined options". Type in Name such as Cisco CallManager, set data type to IP Address and put a check mark next to "array", for code put in 150 then click ok.

You can now either edit the array values to predefine the ip addresses of your call manager or set it per scope.

Now when you configure scope options you should be able to select the newly created option 150 and put in the appropriate Ip addresses.

Set the option to which is the UC500 default TFTP server address.

In addition you need to add a route to your firewall that directs traffic destined to to whatever the data IP of your UC unit is.

Good times!

Community Member

Re: 7921 Loading Problems

Good to hear.


Re: 7921 Loading Problems

I am glad that you solved this, but the 7921 phones looks for a few different IP for its TFTP server.

First, it will look for an Alternate TFTP which you can configure on the phone.

It will look for option 150 in DHCP.

It will look for option 66 in DHCP.

It will try to connect to the default gateway. (I believe this list is correct, it has changed a bit over the years).

Cisco has a doc for configuring Windows server as a DHCP server. (It is for CallManager, but will work with the same for UC500).

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