3.1. Phone extension

Definition phone extension:

An extension is always the internal number, i.e. you reach participants and services within the company without dialing a “0” first. This internal number is completely independent of the direct dial (external number). Extensions could be also defined without a direct dial (just internal extension) or with a different direct dial for an external caller.

How to edit a Phone Extension?

You want to create an extension, which is accessible internally under the number 111, externally by calling +49 123 456789-111 and the phone number +49 123 456789-112. Furthermore, this extension will also have a desk phone as a device. If the extension isn’t available within 30 seconds, the caller will be forwarded to the voicemail of the extension.


  • First, name the extension. Usually the extension name corresponds to the employee's name (example: John Doe).
  • Second, assign an extension number. The employee can now be reached at this extension number within the company. If you have only one trunk line, then a direct dial (external number) is created automatically. If you have multiple trunks, you need to choose a "Preferred Outbound Trunk" in the "Configuration". Afterwards, the direct dial will be created automatically. Then your extension is externally accessible at the direct dial +49 123 456789-111. Insert +49 123 456789-112 in the dialog window "Inbound Numbers" to ensure that your extension is also externally accessible at this number. You also have the option to be available only via the second number.
  • Finally, select a device. You see a drop-down list with all available devices (the MAC addresses of the devices are shown). The device that you select is immediately accessible at the extension.
  • Furthermore, you can also configure the settings such as Voicemail, function keys (BLF), call forwarding, etc. Activate your voicemail and upload your personal announcements, set a parallel ring, if desired, or configure the function keys (BLF) on your desk phone (snom).


Click on Targets in the navigation area. In the main window you can add a new phone extension by clicking the ADD symbol and select phone extension, or double click on an existing phone extension element to change this entry.


You can also define a skill group and skill level in the configuration part of an extension.

A new window with "phone extension" with several sections is shown.


Section Picture
Name and extension 
‌Referenced by
Inbound numbers 
Phone devices
Call forward
Geographical settings
Function keys