Date/Time Impacted

2025-12-18 16:45 UTC - 2025-12-22 12:40 UTC

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Services Impacted

Inbound calls to UK landline and toll-free virtual numbers for Voice API and SIP Trunking.

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Summary

Inbound calls to UK landline and toll-free virtual numbers began experiencing one way audio, where the caller could not hear the recipient. Vonage was alerted to this issue at 2025-12-19 11:51 UTC and swiftly began troubleshooting the issue, confirming the issue to be related at Vonage’s supplier, between the connection of Vonage and the caller. The issue was identified to be affecting all calls and was escalated with the local provider.

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Root Cause

An IP address allow list had been implemented by Vonage’s supplier, without including Vonage’s full range of IP addresses. When Vonage performed routine maintenance on the platform and new IP addresses were allocated to servers, these differed to those present in the allow list by the supplier.

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Restoration Actions

The supplier resolved the issue by allowing RTP traffic from the full range of Vonage IP addresses.

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Next Steps

A programme of improvements including improved notifications and communication with Vonage’s supplier will be delivered. This will prevent future recurrences of the same issue by improving collaboration.