Issue

When attempting to place outbound (or inbound) calls to a specific phone number using Twilio Flex, agents receive the following error message:

"Unable to connect your call. Please try again or contact support. [45301]"

This issue is consistent for all agents and only occurs with the affected number. The error is observed in both inbound and outbound call scenarios. 

It may occur consistently or intermittently when Flex is unable to complete the participant connection. It can affect one or multiple agents and may occur during inbound or outbound call scenarios. In some cases, TaskRouter may successfully create and route the reservation, but the failure occurs afterward when Flex attempts to connect the agent participant to the call.

Product

Twilio Flex

Cause

Error 45301 indicates that Flex could not finish connecting a participant to a call due to a service error. This can be caused by:

• The call not being live or the agent being in another transfer/on hold.
• Insufficient user permissions for call monitoring or joining.
• Recent changes to team ownership/membership not yet reflected in the UI.
• Outdated Flex UI version or Voice SDK registration issues.

Resolution

1. Confirm Call State

• Ensure the call is live and conference-based.

• Verify the agent is not already in another transfer or on hold.

2. Check User Permissions

• Confirm the acting user is an admin or owns the target agent's team.

• If team ownership or membership was recently changed, refresh the Flex UI.

3. Update Flex UI

• Upgrade the Flex UI to the latest version (at least 2.17) to benefit from recent bug fixes, improvements, and enhanced Voice SDK stability.

• See: How To Manage Flex UI Versions and Updates

4. Collect Diagnostic Logs

• Gather browser console logs and HAR files during the failure for further analysis.

• Review Flex error logs in the Debugger and run a System Checkup in the Twilio Console.

5. Check Twilio Platform Status

• Review the Twilio Status Page for any ongoing incidents that may impact call connectivity.

Additional Information 

• Error 45301 is a generic outbound call failure in Flex. If the error persists after following the above steps, further investigation of network, configuration, or platform issues may be required.
• For more details, see the User Guide to Troubleshooting the Flex UI and Twilio Error 45301 Documentation.