Unable to make calls, when we pick up, it shows discretion on the display and we keep gettin a dial tone without being able to dial a number.

SOURCE: My internal Extension

try
feature
the *0
then if you press the last button on the right coloum (line 10)
mine shows up when i try this

hope it helps

SOURCE: No dial tone on receiver only on voice

make shure handset cord is Not pluged in to the Headset jack on the bottom, needs to be in the handset jack (look at the icons)

SOURCE: Norstar M7310- buttons don't produce tone anymore

Have you tried un plugging then plugging them back in to reset them, if not you may have to power cycle the main system.

SOURCE: Nortel M7310 Phone moved to another jack, now no incoming calls

The reason your phones config is not the same as before is because configuration goes by what extension it is. So if you plug your phone in somewhere else, unless you have DN's configured, your extension changes, so say it was extension 21, but now that you moved it, its now 23, those settings remain on extention 21, so if you bought another phone and plugged it into were extention 21 is, it would have the settings that your old phone had before

To access the intercom by just picking up the handset, Press Feature **CONFIG (266344), Select <A. Configuration>, then go to <2. Line Access>, Select that and enter the extension of the phone you want to have access intercom by just picking up the handset. Scroll until you see <Intercom Keys: #,> make sure you have at least one intercom key. Then scroll until you see <Prime Line: #>, Press change until the display reads <Prime Line:I/C>  And there you go. Hope i didn't confuse you 

SOURCE: Display not showing #s

Did your company convert to PRI?