Error CORS when i using SDK "azure/communication-calling"

Question

Error CORS when i using SDK "azure/communication-calling"

Nguyen Uy Dinh 60

I have using SDK "@azure/communication-calling" to create an "call app" using Azure communication service.
I have using api "https://acp-msteams.azurewebsites.net/token" to create account from ACS. Then i use that token, and meeting information (meeting passcode and meeting id) to join a call.

But api "https://api.flightproxy.skype.com/api/v2/cpconv" has fail, and api "https://prod.registrar.skype.com/v3/registrations" has blocked by CORS "Access to fetch at 'https://prod.registrar.skype.com/v3/registrations' from origin 'http://localhost:8080' has been blocked by CORS policy".

This error not show before.
Pls help me to check and resolve this issue.

Thank you.

Laxman Reddy Revuri 5,395 Reputation points Microsoft External Staff Moderator

2025-06-18T04:57:36.2133333+00:00

Hi @Nguyen Uy Dinh
It seems you are encountering a CORS issue while using the Azure Communication Services (ACS) calling SDK. The root issue is that you're trying to directly access Skype backend services like https: These services are used internally by the ACS SDK, and due to tightened CORS policies, they now block direct access from web apps (like localhost:8080).

Do not manually call Skype or Teams APIs. Let the ACS SDK handle those internally just pass in your valid ACS token and meeting info.

Ensure your ACS token endpoint is secure and allows CORS if you're calling it from frontend.

Recheck SDK initialization for CallClient and CallAgent. Any misstep here can cause unexpected network requests.

Occasionally, issues with external services can also cause failures. Verify the Azure Status page to see if there are any ongoing issues with the Communication Services.
https://learn.microsoft.com/en-us/azure/communication-services/concepts/voice-video-calling/calling-sdk-features
PAWAN KUMAR 0 Reputation points

2025-06-18T06:11:02.52+00:00
hi

It seems like you're encountering a couple of issues with CORS (Cross-Origin Resource Sharing) policies and possibly an API failure while working with the Azure Communication Services SDK for creating a call app. Let's break down the issues and how we can resolve them:

Issue 1: CORS Error with https://prod.registrar.skype.com/v3/registrations

The error message:

pgsql Copy Access to fetch at 'https://prod.registrar.skype.com/v3/registrations' from origin 'http://localhost:8080' has been blocked by CORS policy.

This error occurs because the server at prod.registrar.skype.com is not allowing requests from your local development environment (http://localhost:8080) due to CORS restrictions. CORS is a security feature implemented by browsers to prevent unauthorized access to resources on different domains.

Resolution: To resolve this issue during development, you can try a few approaches:

Proxy Server: Set up a proxy server to forward your requests. For example, if you're using Node.js, you can use http-proxy-middleware or similar packages to proxy your requests through your server, which can then forward the request to prod.registrar.skype.com. This way, the request origin will be your server's domain, not localhost, bypassing the CORS restriction.

Here’s a basic example of setting up a proxy in your Node.js server (assuming you are using Node.js for your backend):

javascript Copy const express = require('express'); const { createProxyMiddleware } = require('http-proxy-middleware'); const app = express(); app.use('/api', createProxyMiddleware({ target: 'https://prod.registrar.skype.com', changeOrigin: true, pathRewrite: { '^/api': '/v3/registrations', // Adjust path if necessary }, })); app.listen(8080, () => { console.log('Proxy server running on http://localhost:8080'); });

In your frontend or wherever you make requests, change the URL to http://localhost:8080/api.

Server-side Proxy (Azure Function or similar): Use a serverless function (like Azure Functions) as a proxy to make requests to prod.registrar.skype.com from a domain that does not have CORS restrictions.

Backend Service: If you have a backend service (like Azure App Service) that serves your frontend, make the request to prod.registrar.skype.com from your backend service and expose an endpoint on your backend that your frontend can call.

Issue 2: Failure with https://api.flightproxy.skype.com/api/v2/cpconv

You mentioned that this API call is failing. To address this:

Check if the API endpoint https://api.flightproxy.skype.com/api/v2/cpconv is still valid and if there are any recent changes or outages from the service provider (Microsoft or Skype).

Ensure that you are sending the correct parameters and headers required by the API. Sometimes, API failures can be due to incorrect payload or missing headers.

Review the Azure Communication Services SDK documentation or any specific guidelines provided by Microsoft for integrating with Skype APIs to ensure you are using the correct endpoints and protocols.It seems like you're encountering a couple of issues with CORS (Cross-Origin Resource Sharing) policies and possibly an API failure while working with the Azure Communication Services SDK for creating a call app. Let's break down the issues and how we can resolve them: Issue 1: CORS Error with https://prod.registrar.skype.com/v3/registrations The error message:
pgsql Copy Access
This error occurs because the server at prod.registrar.skype.com is not allowing requests from your local development environment (http://localhost:8080) due to CORS restrictions. CORS is a security feature implemented by browsers to prevent unauthorized access to resources on different domains. Resolution:
To resolve this issue during development, you can try a few approaches:

Proxy Server: Set up a proxy server to forward your requests. For example, if you're using Node.js, you can use http-proxy-middleware or similar packages to proxy your requests through your server, which can then forward the request to prod.registrar.skype.com. This way, the request origin will be your server's domain, not localhost, bypassing the CORS restriction. Here’s a basic example of setting up a proxy in your Node.js server (assuming you are using Node.js for your backend):
javascript Copy const
In your frontend or wherever you make requests, change the URL to http://localhost:8080/api.

Server-side Proxy (Azure Function or similar): Use a serverless function (like Azure Functions) as a proxy to make requests to prod.registrar.skype.com from a domain that does not have CORS restrictions.

Backend Service: If you have a backend service (like Azure App Service) that serves your frontend, make the request to prod.registrar.skype.com from your backend service and expose an endpoint on your backend that your frontend can call.

Issue 2: Failure with https://api.flightproxy.skype.com/api/v2/cpconv You mentioned that this API call is failing. To address this:

Check if the API endpoint https://api.flightproxy.skype.com/api/v2/cpconv is still valid and if there are any recent changes or outages from the service provider (Microsoft or Skype).

Ensure that you are sending the correct parameters and headers required by the API. Sometimes, API failures can be due to incorrect payload or missing headers.

Review the Azure Communication Services SDK documentation or any specific guidelines provided by Microsoft for integrating with Skype APIs to ensure you are using the correct endpoints and protocols.
Nguyen Uy Dinh 60 Reputation points

2025-06-18T06:45:44.61+00:00

hi @Laxman Reddy Revuri @PAWAN KUMAR
Thank you guys to answer and supported me in this issue.

I understand the solution you suggested to me.
BUT, the problems is this error show when i using SDK "azure/communication-calling" by using "callAgent.join" this api not call manually by me, but it call by SDK "azure/communication-calling", specifically by function "callAgent.join"

But this issue just show a few day, it not show this error before.
It just show when i using ACS account (create new ACS account), it not show, when i using account exchange Microsoft Team token -> ACS token

do you guys have any idea about this?
Nguyen Uy Dinh 60 Reputation points

2025-06-18T07:17:19.46+00:00

hi @Laxman Reddy Revuri
Thank you for this new information, do you have any document about this information?
And is there any document about which permission is need for Direct ACS users (created using CommunicationIdentityClient)?
Laxman Reddy Revuri 5,395 Reputation points Microsoft External Staff Moderator

2025-06-18T09:06:07.96+00:00

Hi @Nguyen Uy Dinh
There is official Microsoft documentation that confirms Direct ACS users created via CommunicationIdentityClient do not require any specific Azure or Microsoft Teams permissions. Their ability to join Teams meetings is managed entirely through Teams tenant-level settings, not through individual permissions.
Nguyen Uy Dinh 60 Reputation points

2025-06-18T09:08:58.9033333+00:00

thanks @Laxman Reddy Revuri i will check information in Microsoft document call and ACS

Accepted answer

0 additional answers

Your answer

Laxman Reddy Revuri 5,395 Reputation points Microsoft External Staff Moderator

2025-06-18T04:57:36.2133333+00:00

Hi @Nguyen Uy Dinh
It seems you are encountering a CORS issue while using the Azure Communication Services (ACS) calling SDK. The root issue is that you're trying to directly access Skype backend services like https: These services are used internally by the ACS SDK, and due to tightened CORS policies, they now block direct access from web apps (like localhost:8080).

Do not manually call Skype or Teams APIs. Let the ACS SDK handle those internally just pass in your valid ACS token and meeting info.

Ensure your ACS token endpoint is secure and allows CORS if you're calling it from frontend.

Recheck SDK initialization for CallClient and CallAgent. Any misstep here can cause unexpected network requests.

Occasionally, issues with external services can also cause failures. Verify the Azure Status page to see if there are any ongoing issues with the Communication Services.
https://learn.microsoft.com/en-us/azure/communication-services/concepts/voice-video-calling/calling-sdk-features
Nguyen Uy Dinh 60 Reputation points

2025-06-18T06:45:44.61+00:00

hi @Laxman Reddy Revuri @PAWAN KUMAR
Thank you guys to answer and supported me in this issue.

I understand the solution you suggested to me.
BUT, the problems is this error show when i using SDK "azure/communication-calling" by using "callAgent.join" this api not call manually by me, but it call by SDK "azure/communication-calling", specifically by function "callAgent.join"

But this issue just show a few day, it not show this error before.
It just show when i using ACS account (create new ACS account), it not show, when i using account exchange Microsoft Team token -> ACS token

do you guys have any idea about this?
Nguyen Uy Dinh 60 Reputation points

2025-06-18T07:17:19.46+00:00

hi @Laxman Reddy Revuri
Thank you for this new information, do you have any document about this information?
And is there any document about which permission is need for Direct ACS users (created using CommunicationIdentityClient)?
Laxman Reddy Revuri 5,395 Reputation points Microsoft External Staff Moderator

2025-06-18T09:06:07.96+00:00

Hi @Nguyen Uy Dinh
There is official Microsoft documentation that confirms Direct ACS users created via CommunicationIdentityClient do not require any specific Azure or Microsoft Teams permissions. Their ability to join Teams meetings is managed entirely through Teams tenant-level settings, not through individual permissions.
Nguyen Uy Dinh 60 Reputation points

2025-06-18T09:08:58.9033333+00:00

thanks @Laxman Reddy Revuri i will check information in Microsoft document call and ACS

Answer 1

Laxman Reddy Revuri 5,395 Microsoft External Staff Moderator

Hi @Nguyen Uy Dinh
Apologize for any inconvenience caused on this.

You’re seeing the CORS error when using callAgent.join() with newly created ACS users because Microsoft has recently tightened policies for Teams interoperability.

Only ACS tokens associated with a Microsoft Teams user identity (via Entra ID and Teams license) can join Teams meetings as full Teams participants. Direct ACS users (created using CommunicationIdentityClient) can still join Teams meetings as external guests, but with limited capabilities. If your ACS user is not properly federated or lacks the necessary permissions, the SDK’s internal calls to Teams backend services will fail, resulting in CORS errors.
https://learn.microsoft.com/en-us/azure/communication-services/concepts/interop/enable-interoperability-teams

Laxman Reddy Revuri 5,395 Reputation points Microsoft External Staff Moderator

2025-06-18T09:12:15.5333333+00:00

Hi @Nguyen Uy Dinh
Please accept as "Yes" if the answer provided is useful, so that you can help others in the community looking for remediation for similar issues.

Share via

Error CORS when i using SDK "azure/communication-calling"

0 additional answers

Your answer