Polycom 500 2G4 - Manual (Page 6)

How to Register a Master Handset
1–3
Right after this has been done, the handset will ask for an extension number.
Simply enter the extension number. Then press the ✓key (can be the ”old”
extension number used on the corded phone. Or alternatively any number
available in the PABX).
The MASTER handset has now ” allowed ” the system to register the new
handset to the system. You can now register the handset following the
procedure used when registering the MASTER handset. By pressing < once
you will return to the registration menu. More handsets can be registered
following the same procedure.
How to Delete a Registered Handset
Enter the menu ”EXT.Service”.
The menu is called ”Delete_user_info”
When choosing this menu, you will see the same menu structure as above.
Instead you choose the Serial Number to be deleted and press the ✓key.