Hello Soundhar M, to purchase phone numbers in Azure Communication Services, you need to have a subscription that supports phone number capabilities. Currently, phone number capabilities are available in the following subscription offers:
- Microsoft Customer Agreement (Field and Customer Led)
- Modern Partner Agreement (CSP)
- Enterprise Agreement
- Pay-As-You-Go
Subscription eligiblity offers changes based on the country in which you're trying to puchase the phone number. You would want to keep a tab on this page -- https://learn.microsoft.com/en-us/azure/communication-services/concepts/numbers/phone-number-management-for-united-states.
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