atcomsystems.ca/forum Forums TDM Business Telephone Systems Samsung Telephones & Systems (2) 6021 IP phones keep intermittently swapping extension numbers

OS-7100, software 4.99, 6021 phones are at v1.40

We have two IP phones (remote) that work fine as far as placing/receiving calls. They are extension 179 & 181. At some point a couple months after installation, these two extensions will intermittently swap their extension numbers. Here's what I mean. If you have a 6021 phone programmed, then you will see that extension number in a little black box in the upper left corner of the display. If you lift the handset, then just under the little black box with the extension number in it, you'll see your extension number there as well. Here's the issue. When X179 goes offhook, right below the extension in the black box it will then show 181. Then I go to the other phone which is displaying 181, lift the handset and it shows 179. If you place a call - the extension number showing when you lift the handset is what's displayed.

Now - when this happens...it will go back as well. Here's what I've done to try and isolate so far.

-In 2.7.1 I swap the user ID's and then have them reboot the phones. Things are fine for a while - then they swap again.
-In 6.3.15 I completed CLEAR REGISTRATION & FORCED LOGOUT
-In 6.3.5 I completed PORT CLEAR for the two affected extensions
-Rebooted each phone
-Reviewed settings in the phone to make sure there were not multiple servers configured

What mac addresses show up?
Are these phones in the same place?
What Do you have set as the pnp mode in 5.2.10?

-Phones are in the same office - both running off different ports on their Gigabit switch.
-Noticed that Auto PnP was set. Looked at some other systems and that appears to be the default. Changed to NORMAL LOGIN, system restarted and we'll see what happens.

Appreciate the response!