ACS Phone Number Configuration

Hi @SunnyT ,

Welcome to Microsoft Q&A Platform. Thank you for reaching out.

First of all, let me answer to your questions

1) Can I create a “self‑defined” number in ACS? Why is Get greyed out?

ACS doesn’t allow you to type in or define a random number yourself. Instead, you have three official options:

Buy numbers directly from Microsoft (ACS): You can purchase numbers only if your Azure subscription and billing address are eligible for PSTN services in your country or region. Eligibility varies by country because of telecom regulations. If your country isn’t supported, the “Get” button will appear greyed out.

Port existing numbers into ACS: If you already have phone numbers with another carrier, you can transfer (port) them into ACS. This isn’t automated it’s a manual porting process handled through the ACS number porting workflow.

Use Direct Routing with your own carrier (BYOC): You can keep your existing numbers with your current carrier and connect them to ACS via Direct Routing using a Session Border Controller (SBC). In this case, ACS doesn’t host your numbers; it just routes call through your SBC.

Common Reasons the “Get” Button Is Greyed Out:

Subscription or country not eligible: If your Azure billing address isn’t in a supported region, you won’t be able to buy numbers the UI disables the option.

Trial numbers limited to US billing addresses: Only subscriptions with US billing addresses can get trial phone numbers.

Quota or manual order required: The self-service portal sometimes limits how many numbers you can get (for example, only one). For larger requests or unsupported countries, you need to use the Special-Order process by emailing acstns@microsoft.com.

2) Do I need a “Phone Standard / Teams Phone” license in ACS like Teams Direct Routing?

How Licensing Works in ACS:

ACS operates as a Communication Platform as a Service (CPaaS). That means it uses a consumption-based billing model you only pay for what you use, such as:

Call minutes (inbound and outbound)

Phone numbers (if hosted by Microsoft)

SMS messages

Call Automation or Calling SDK usage

There are no per-user or seat-based licenses in ACS. You don’t assign licenses to individuals to make or receive calls you simply consume the services and pay accordingly.

How This Differs from Microsoft Teams:

In contrast, Microsoft Teams Direct Routing requires each user who wants to make or receive PSTN calls to have a Teams Phone license (previously called Phone System license). This license enables PBX-like calling features for each user inside Teams.

In short, ACS is pay-as-you-go, while Teams Direct Routing is license-based.

It’s important to understand that Teams Direct Routing and ACS Direct Routing are two completely different integrations, even though they share the same term “Direct Routing.”

Here’s the clear distinction:

Teams Direct Routing

• The Session Border Controller (SBC) connects directly to Microsoft 365 / Teams.
• Incoming and outgoing calls are handled through Teams users.
• Each user involved in PSTN calling must have a Teams Phone (formerly Phone System) license.
• This setup is part of the Microsoft Teams enterprise telephony ecosystem.

ACS (Azure Communication Services) Direct Routing

• The SBC connects to an ACS resource in Azure not to Microsoft 365 or Teams.
• Calls are routed to ACS identities or handled by your Call Automation application.
• The SBC must be separately paired with ACS, independent of any Teams configuration.
• Best practice: Use an FQDN (Fully Qualified Domain Name) for your SBC that is not already registered in Office 365 to avoid conflicts. It’s important to understand that Teams Direct Routing and ACS Direct Routing are two completely different integrations, even though they share the same term “Direct Routing.” Here’s the clear distinction:

Your Session Border Controller (SBC) is already paired and showing as Online, which means the connection itself is working correctly.

However, the issues you’re currently facing are related to two main factors:

How Azure Communication Services (ACS) manages phone numbers, and

How inbound and outbound call routing is configured for ACS Direct Routing.

How Azure Communication Services (ACS) Manages Phone Numbers

ACS handles phone numbers through its Telephony and SMS capabilities:

• Provisioning: You cannot create custom numbers; ACS provides numbers through its inventory. Numbers can be purchased or ported from existing carriers (porting requires a formal process). Availability depends on region and country compliance. Check ACS Phone Number Availability.
• Types of Numbers: Toll-Free: For customer service or large-scale messaging. Geographic: Local numbers for voice and SMS. Short Codes: For high-volume SMS (requires regulatory approval).
• Management: Numbers are tied to an ACS resource.
• Billing is based on: Monthly number rental. Usage (voice minutes, SMS messages). No per-user license like Teams; ACS uses application identities.

How Call Routing Works with ACS Direct Routing

Direct Routing in ACS lets you connect to the PSTN (traditional phone network) through a Session Border Controller (SBC). Here’s what happens:

Outbound Calls (ACS > PSTN)

• Your app (web, mobile, or server) starts a call using the ACS Calling SDK.
• ACS sends the call to your SBC using the FQDN you configured.
• The SBC takes care of: SIP signaling (the protocol for setting up calls). Media negotiation (audio/video streams). Routing the call to the PSTN or your internal PBX.

What You Need for This to Work:

• SBC must be accessible over TLS (secure connection).
• SIP trunk configured for your ACS domain.
• Telephony features enabled on your ACS resource.

How Call Routing Works with ACS Direct Routing

Direct Routing in ACS lets you connect to the PSTN (traditional phone network) through a Session Border Controller (SBC). Here’s what happens:

Outbound Calls (ACS > PSTN)

• Your app (web, mobile, or server) starts a call using the ACS Calling SDK.
• ACS sends the call to your SBC using the FQDN you configured.
• The SBC takes care of: SIP signaling (the protocol for setting up calls). Media negotiation (audio/video streams). Routing the call to the PSTN or your internal PBX.

What You Need for This to Work:

• SBC must be accessible over TLS (secure connection).
• SIP trunk configured for your ACS domain.
• Telephony features enabled on your ACS resource.

Reference :

https://learn.microsoft.com/en-us/azure/communication-services/quickstarts/telephony/get-phone-number?tabs=windows&pivots=platform-azp-new

https://learn.microsoft.com/en-us/azure/communication-services/how-tos/call-automation/teams-interop-call-automation?pivots=programming-language-javascript

https://learn.microsoft.com/en-us/azure/communication-services/quickstarts/telephony/pstn-call?pivots=platform-web

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Hi @Hi @SunnyT ,

Could you please review my comments, follow the steps, and let me know whether your issue has been resolved?