When unable to dial numbers, using a service plan, the most probable cause is the wrong dial plan set on the phone/UAD from which call is being placed.

Example:
Dialing *1991002 will fail as soon as you reach digit '1', or any former or latter digit.

Solution:
In your web browser, open your phone/UAD IP address and according to the manufacturer's manual, update the phone/UAD dial plan.

A dial plan for Sipura SPA-941 would look like this:
*x.|**x.|*xx|[3469]11|0|00|[2-9]xxxxxx|1xxx[2-9]xxxxxx|xxxxxxxxxxxx.

Note:
After making any changes to the phone/UAD dial plan, please save settings and reboot the phone/UAD if that is not done automatically