Where are Call Manager Subscriber Addresses stored on the 88xx phones?

[ricky-ho]

Where is the tertiary Call Manager (subscriber #2) IP address stored on an 88xx phone?

Our Publisher and Subscriber 1 are in the same datacenter1, while Subscriber 2 is in datacenter2.

We are planning to do maintenance on datacenter1 but want to confirm that the phones will know the IP address Subscriber2 to re-register.

Our CM Group Configuration does specify the order of Sub1, Sub2, Pub.

[Roger Kallberg]

It gets its configuration from CM TFTP service and stores it in NVRAM on the phone.

[ricky-ho]

Is this simply hidden on the phone itself?
When looking at Phone Info on the phone, it shows primary TFTP and secondary TFTP IP addresses, which are the addresses of the PUB and SUB1. I don't see SUB2 IP address anywhere.

[Maren Mahoney]

The TFTP servers are shown in a list along with other Network information because the phone needs that information to register. Elsewhere in the menu on the phone are the Primary, Secondary, and Tertiary call processing nodes that they will register to.

In my system (and Cisco moves this sometimes with new firmware) they are shown by pressing the Settings button and then accessing the "Phone Information" menu. Scroll to the very bottom and you will see the call processing nodes listed as "Active Server" and "Stand-by Server".  We only have two. Presumably in your system it will show all three.

Maren

[ricky-ho]

I had mistaken TFTP for Active Server - 

Yes I also have Active Server and Stand-by Server in my Phone Information menu, but it's showing the PUB and SUB1, respectively.

No mention of SUB2. Does that mean if my PUB and SUB1 go offline, the phone will be unable to register to SUB2, as it doesn't have the IP address listed?

[Maren Mahoney]

Not necessarily. If the CallManager Group that is assigned to the phone (via the Device Pool) lists all three call processing nodes, then the phone 'knows' about all three. A phone will fully register to its primary server, do a regular checkin with its secondary server, but won't reach out to its tertiary server unless both of the other two go down. So it's possible the third server is just not listed.

So double-check the CallManager Group to make sure all three are assigned. You can also look at the phone's web page (if it is enabled - http://<ip.of.phone> ) and all three should be listed if all three are in the CMG.

Maren

[Roger Kallberg · Accepted solution]

One small correction, the phone will initiate a connection to the tertiary server if one of the primary or secondary servers go down. If the primary goes down the secondary will be promoted to primary and then the tertiary server becomes the secondary and if the secondary goes down the tertiary server becomes the secondary, but the phone keeps the connection with its primary server.

This is how it looks on the web page of a phone, in this case a 8851.

The 4 one in this case is the TFTP server.

[Maren Mahoney]

Yep, @Roger Kallberg is right about the phone reaching out to its tertiary as soon as one of the others goes down. Not enough coffee today.

Maren

[ricky-ho]

Ah, thank you both.

I was able to connect to the phone via https and confirm that CUCM server1-3 are all listed there.

Thanks for the explanation.

[Roger Kallberg]

Looking at the same device via a remote control tool to see what is actually displayed on the device itself this is what it shows.

So the device itself shows two servers, even if there are more visible on the web page.