I cannot address issues with the Dinstar and I do not know what digits the mobile carrier is looking for. I can provide you a basic dial plan for the PBX that may assist you. This is based on the UAE published telephone numbering plan published here: Telephone numbers in the United Arab Emirates - Wikipedia
The attached image would be the dial plan for your outbound route. If you dial an access code such as “9” to reach an outside line, you would put the digit in the prefix field so that it is stripped out of the number that is sent to your carrier.