Hi @IBN
When attempting to transfer a call in Microsoft Teams, we encounter the following error 503 Service Unavailable.
Did this user transfer the one-on-one calls in Teams like this article's description?
Does anyone else have the same problem in your organization?
Based on my knowledge, a 503 Service Unavailable Error indicates that a web server is temporarily unable to handle a request. The error can occur for a number of reasons, but the two most common reasons are that the server is overwhelmed with requests or is having maintenance performed on it.
If your organization's user meet this problem, it firstly recommends try to see if Teams web client can transfer call normally. If there is no issue in Teams web client, please try to follow these steps to clear Teams client cache file to see if it works:
- Fully quit Microsoft Teams and ensure it’s not still running in the toolbar at the bottom right of Windows.
- Navigate to %appdata%/Microsoft/Teams in a File Window.
- Select everything in the folder.
- Delete everything.
- Open Teams and wait for it to download required files.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.