Need to remove 2-call limit for PSTN during app development for Communication Services

Question

Need to remove 2-call limit for PSTN during app development for Communication Services

Mian Omair 0

We are currently developing an AI-powered voice calling agent using Azure Communication Services (ACS) for our client, a healthcare alert system provider.

Project Overview:

This solution leverages:

Azure Functions (FastAPI integration via AsgiFunctionApp)
Azure Cognitive Services (Speech) for TTS
ACS Call Automation SDK for outbound PSTN calls

The voice agent generates custom TTS scripts to send flu shot reminders and other health-related messages. These are tested in a live call flow and refined iteratively.

Issue:

We acquired a trial toll-free number through ACS, but it enforces a hard limit of 2 PSTN calls per number.

This limit severely restricts our development process. We need to perform multiple test calls to a single verified number (a developer’s test phone) to validate TTS generation, call triggering, and webhook behavior.

Request:

We kindly request a temporary removal or increase of this 2-call limit on the assigned number or allow development calls to a fixed test number during our dev cycle.

We are not using this for production or spam. It is strictly a verified internal number for iterative testing during ACS voice agent development.

Prabhavathi Manchala 1,220 Reputation points Microsoft External Staff Moderator

2025-04-23T21:22:27.39+00:00

Hi Mian Omair,

Your team is building an AI voice agent with Azure Communication Services (ACS) for a healthcare alert system, using Azure Functions, Cognitive Services for TTS, and ACS Call Automation SDK to deliver health messages. The 2-call limit per toll-free ACS number is making it hard to test and refine the system, as multiple test calls are needed to validate TTS, call triggering, and webhook behaviour.

This 2-call limit is a safeguard on trial phone numbers to prevent misuse and spam, and it can't be bypassed for development purposes. To continue testing without delays, the best solution is to upgrade to a paid Azure Communication Services resource. You can then purchase a dedicated phone number (toll-free or geographic), which has no PSTN call limits, allowing you to make multiple test calls.

Please check the links below for information on PSTN call limits and pricing.

Service limits for Azure Communication Services - An Azure Communication Services article | Microsoft Learn

Pricing for PSTN - An Azure Communication Services concept document | Microsoft Learn
Prabhavathi Manchala 1,220 Reputation points Microsoft External Staff Moderator

2025-04-24T18:59:33.6266667+00:00

Hi Mian Omair,

We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution, please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.
Prabhavathi Manchala 1,220 Reputation points Microsoft External Staff Moderator

2025-04-25T19:27:38.88+00:00

Hi Mian Omair,

We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution, please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.
Sampath 2,925 Reputation points Microsoft External Staff Moderator

2025-04-28T04:22:57.7933333+00:00

Hi @ Mian Omair, requesting you check private messages and reply there. Thank you.
Sampath 2,925 Reputation points Microsoft External Staff Moderator

2025-04-30T06:04:37.96+00:00

Hello @Mian Omair,

we are waiting for your response.

1 answer

Your answer

Prabhavathi Manchala 1,220 Reputation points Microsoft External Staff Moderator

2025-04-23T21:22:27.39+00:00

Hi Mian Omair,

Your team is building an AI voice agent with Azure Communication Services (ACS) for a healthcare alert system, using Azure Functions, Cognitive Services for TTS, and ACS Call Automation SDK to deliver health messages. The 2-call limit per toll-free ACS number is making it hard to test and refine the system, as multiple test calls are needed to validate TTS, call triggering, and webhook behaviour.

This 2-call limit is a safeguard on trial phone numbers to prevent misuse and spam, and it can't be bypassed for development purposes. To continue testing without delays, the best solution is to upgrade to a paid Azure Communication Services resource. You can then purchase a dedicated phone number (toll-free or geographic), which has no PSTN call limits, allowing you to make multiple test calls.

Please check the links below for information on PSTN call limits and pricing.

Service limits for Azure Communication Services - An Azure Communication Services article | Microsoft Learn

Pricing for PSTN - An Azure Communication Services concept document | Microsoft Learn
Prabhavathi Manchala 1,220 Reputation points Microsoft External Staff Moderator

2025-04-24T18:59:33.6266667+00:00

Hi Mian Omair,

We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution, please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.
Prabhavathi Manchala 1,220 Reputation points Microsoft External Staff Moderator

2025-04-25T19:27:38.88+00:00

Hi Mian Omair,

We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution, please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.
Sampath 2,925 Reputation points Microsoft External Staff Moderator

2025-04-28T04:22:57.7933333+00:00

Hi @ Mian Omair, requesting you check private messages and reply there. Thank you.
Sampath 2,925 Reputation points Microsoft External Staff Moderator

2025-04-30T06:04:37.96+00:00

Hello @Mian Omair,

we are waiting for your response.

Answer 1

Sampath 2,925 Microsoft External Staff Moderator

Hi @ Mian Omair,

The Default number of outbound concurrent calls Per number is limited to 2.There are no limits on inbound concurrent calls. You can also submit a request to Azure Support to increase the limit for outbound concurrent calls. Our vetting team reviews all requests. Refer this doc to increase throttling limits .

If you encounter any issues, please let us know in the comments. If this helped, let us know in the comments and give a vote. Thank you.

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Need to remove 2-call limit for PSTN during app development for Communication Services

1 answer

Your answer