IP Office Essential Edition mode systems can use 2-digit or 3-digit numbering. In 2-digit systems, the user extensions are fixed as 10 to 57. In 3-digit systems, the user extensions are numbered 100 upwards by default but can be renumbered in the range 100 to 579.
In 2-digit mode, only 48 extensions are supported, in 3-digit mode a maximum of 100 extensions are supported. It is strongly recommended that these options are only used and changed on a newly installed system.
To change the numbering mode:
1.Within the system configuration select Tools | Extension Renumber.
•Default Numbering
Select whether the systems uses 2 Digit or 3 Digit extension numbering. In 2 digit systems, the user extensions are fixed as 10 to 57. In 3 digit systems the user extension are numbered 100 upwards by default but can be renumbered. In 2 digit mode only 48 extensions are supported, in 3 digit mode a maximum of 100 extensions are supported.
•Renumber From/Renumber To
These options are available for systems set to 3 Digit numbering. They can be used to renumber select extensions.
2.Continue with the basic configuration or click on the 
save icon to save the updated configuration and then continue.