I think malcolmd is trying to hint that responsible PSTN gateways will not allow you to set a number other than one that they have allocated to you for inbound calls.
If your provider is not restricting the numbers, please provide an example of part of the configuration that does result in the correct number being displayed.
Also, it looks to me that the use of $[] will cause variable length numbers, as it may cause leading zeroes to be stripped in the retained part of the extension number.
i connet to my providers citrix system and my inner number on their system is— 1038323550----
when someone is calling me he dials 021683550, and he reaches me, but when i call him on his telephone my number is not shown, and it needs to show 021683550