On Friday, Sep 19, 2025 at 11.21pm UTC, we rolled out a change to our SIP gateway servers that reduced the allowed MTU size for incoming packets to 1500 bytes. While this did not affect all calls, 5% of calls where INVITE messages exceeded the SIP mandated MTU size of 1500 got dropped. These may have appeared like network issues to any affected users. The fix was to increase the MTU size limit on the SIP gateway and this resolved the issue. To prevent similar incidents in the future, we have already added to both our monitoring and our release verification suite to cover this case.