I`m not sure how familiar you are with programming but here goes. It`s not that easy if you`re not familiar. I am going by memory, but you can give it a try if you like. Before you try my steps, you could just try swapping the phones and see if the extensions move with them. If it doesn`t move them back and try the following steps.
From a 7310 or 7324 telephone follow the following steps
Feature **266344
Password 266344
It will come up Terminals and Sets
Three (4, once you enter a heading) buttons light up.
Hit the bottom right button of the three thats lit up (next) until you get to system programming. Hit the top right button (show). Hit the bottom right one until you get to feature settings. Hit the top right button. Hit the bottom right button until you get to set relocate. If it is set to Y (yes) release and swap your phones. If its set to N change it to Y and release. If at any time you get to somewhere that doesn`t seem to match my steps, release and try again. You can really mess up your system if you go into this area that is designated for installers. If it doesn`t work the second time, let me know and I`ll repeat it with the manual in front of me.
Set relocate enables phones that you move around to carry the extension and programming along with it. Good luck.
Schlum