Thanks for asking question! Just to confirm If you are using trial accounts or by Azure free credits? You may want to know that
Phone number availability is currently restricted to paid Azure subscriptions that have a billing address in the United States and Communication Services resources that have a US data location.
Phone numbers cannot be acquired on trial accounts or using Azure free credits. For more information, visit the subscription eligibility section of this document.
Reference: https://learn.microsoft.com/en-us/azure/communication-services/concepts/telephony-sms/plan-solution
Let us know if you have further query on this or issue remains.