Hello Milo last,
Did a quick check and you are correct calling plans are not available in your region. https://learn.microsoft.com/en-us/microsoftteams/phone-reference/plan-availability/availability-in-saudi-arabia
Parting from the above you would need to use a PSTN option. There are 4 main ones, and they are described in this article https://learn.microsoft.com/en-us/MicrosoftTeams/pstn-connectivity. Based on your description I believe your option is "Operator Connect", but again there might be some details I am unaware of.
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