Teams reply with 503 Service Unavailable

IBN 4,321 Reputation points


Please I need support on this issue.

I have a colleague who is complaining about an issue.

When attempting to transfer a call in Microsoft Teams, we encounter the following error:

SIP/2.0 503 Service Unavailable
FROM: ;tag=1c1921251026
TO: ;tag=f9f7211729fe400baf40e8ff917d5eab
CALL-ID: 873532469261202211548 @ sbc1. marexspectron. com
VIA: SIP/2.0/TLS sbc1. marexspectron. com:5068;branch=z9hG4bKac420436637
REASON: Q.850;cause=42;text="290e551c-a442-4bdb-b437-9b052dd022f2;Inactive, please retry."
SERVER: Microsoft.PSTNHub.SIPProxy v.2022.1.18.11 i.USEA.0

This happens intermittently.
Please can you help us troubleshoot this issue?

This is known to happen randomly throughout the day but not every day.
Potentially, all of our users on Teams via the SBC so approx. 150.

We’ve investigated this with the vendor of our SBC’s and they’ve confirmed the error seen in the syslog relates to Microsoft Teams not being able to transfer the call.

This happens intermittently

Please can you help us troubleshoot this issue?

@Sameh's Learning Zone Mohamed Naguib @Elsie Lu_MSFT @Yi Lu_MSFT @Zhengqi Lou-MSFT @Sayali-MSFT @JimmyYang-MSFT @Faery Fu-MSFT @Vasil Popov Sr Michev @Dominik m @Yuki Sun-MSFT

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  1. JimmyYang-MSFT 48,536 Reputation points Microsoft Vendor

    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:

    1. Fully quit Microsoft Teams and ensure it’s not still running in the toolbar at the bottom right of Windows.
    2. Navigate to %appdata%/Microsoft/Teams in a File Window.
    3. Select everything in the folder.
    4. Delete everything.
    5. Open Teams and wait for it to download required files.

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