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Applies to VoipNow 3 and higher!

This article provides important details about both the extensions' short and extended number.

How extension numbers are generated 

By default, VoipNow generates extension numbers in the following format:



  • XXXX is the organization's number, which is automatically generated for each new account starting with 0003 (0003 is the first possible organization).
  • XXX is the extension's number, which has three digits by default.
  • * is the default separator.

Why you need extended numbers 

Extended numbers are used to differentiate extensions that belong to different organizations so that they can have the same extension numbers.

For example, organization 0003 has 0003*001 and organization 0004 has 0004*001. Both organizations have the same extension number, 001, even if the two extensions are completely different.

Extended numbers are also used when extended local calls are made. For example, between different organizations, when the called extension does not have a public phone number associated.

How and when to change extended numbers

The extension number length (the digits after the separator) and the separator can only be changed if no extensions have been created on the server. Because there can only be one format for all the extensions on a server.

If there are extensions on the server and you want to change the format, the first thing to do is remove them. 

To change the extension's length or separator, follow the steps below:

STEP 1: Log in to the VoipNow web interface.

STEP 2: Go to the Unified Communications → Zero Priority page, select the SIP tab and modify the following fields:

  • Extension number length
  • Separator between client ID and the extension number

Please note these fields will be grayed out if there are extensions on your server.

How and when to change short numbers

An extension's short number (the digits after the separator) can be changed when the extension is created.

The short number needs to be unique as two extensions that belong to the same organization cannot have the same number. Once the extension has been created, the number cannot be modified.

If you need to change an extension's number, you have to delete the extension first and set it up again with the new number.

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