Setting Grandstream Extension Numbers to 3-digit

Most business phone users are accustomed to 3-digit extensions.  When confronted by 4-digit extensions, it can be confusing.

It is very simple to change the length of the digits and their designations

From the menus select:

1. PBX
2. Internal Options
3. General               
1. Enter the Following:
• User Extensions                               100         629
• Pick Extensions                                400         499
• Auto Provision Extensions                300         350
• Conference Extensions                     630         639
• Ring Group Extensions                     640         649
• Queue Extensions                             650         659
• Voicemail Group Extension               660         669
• IVR Extensions                                  670         679
• Dial By Name Extensions                  680         689
• Fax Extension                                    690         699

For most of the changes are simply removing the last digit of the 4-digit number.  However, you cannot have an extension in the 700 range.  So the last three groups are adjusted to fit below 700.  ( Yellow highlighted section)