This tool can be used to change the numbering of user extensions in a system between 2-digit and 3-digit. For 3-digit systems it can also be used to change the numbering of the extensions whereas 2-digits systems use the fixed extension numbers 10 to 57.

It is strongly recommended that these options are only used and changed on a newly installed system. Changing extension numbering affects other services including voicemail and may require extension reconfiguration of hunt groups and trunk call routes.

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 selected extensions. The extension numbers are restricted to the range 100 to 579.