Numberplan & Prefix

It is advised to maintain a logical structure for the allocation of external and internal numbers (which also call forwards). An example:

A company has a number block of 100 numbers: 088–55332xx. These can be then classified as follows.

  • 088–5533200 Main Number
  • 088–5533201 - 088–5533209 Special numbers (such as conference speakers and / or office numbers)
  • 088–5533210 - 088–5533299 Direct numbers for employees.

The last few digits of the direct number can also be used for internal numbers, for example: 210–299. This has a great advantage. Because the last digits of the direct number are the same as the internal number it makes it far easier to remember.


If for each user also an external number is created, or there are multiple external numbers per department, then a prefix could be useful.

This ensures that a call to an external number which is forwarded to another user, displays the name of the originally called user. To do this, place a prefix element before the user element.

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