How can i change my extension nuber (norstar M7310)

Sorry can you clairify this question...

-> You need a new extension number for your set?
-> You need a new extension on your set so you can see when they are on their phone?

If it is the first, there are many things that you need first, too much to explain at the moment. But you need to have the password and a template for your phone to make changes.

If it is the second, press:
- Feature * 0 and any button to find out what is on the button, look for an empty button or one that you want to overwrite,
- then RLS,
- press FEATURE * 2
- press the button where you want to add this new extension
- dial the extension of the new person

Voila you are done!

Good luck!