@Aaush Thanks for reaching here! You may want to know that-
SMS and PSTN capabilities depend on the phone number you use and the country/region that you're operating within as determined by your Azure billing address. For more information, visit the Subscription eligibility documentation.
Numbers can be purchased on eligible Azure subscriptions and in geographies where Communication Services is legally eligible to provide them.
Suggest you to share your scenario and scope of application, to help you better here.
Please let us know.