Duo Security experienced a major incident on August 6, 2025 affecting SMS Message Delivery and SMS Message Delivery and 1 more component, lasting 3h 25m. The incident has been resolved; the full update timeline is below.
Affected components
Update timeline
- investigating Aug 06, 2025, 04:40 AM UTC
We are investigating an issue causing SMS delivery delays and failures in the US. We are waiting for AT&T to fix the issues on their end. During this time, please use alternate authentication methods such as Duo Push, Duo Mobile Passcodes, Hardware Tokens etc to login to your Duo-protected integrations.
- identified Aug 06, 2025, 04:49 AM UTC
We have identified an issue causing SMS delivery delays and failures in the US. We are waiting for AT&T to fix the issues on their end. During this time, please use alternate authentication methods such as Duo Push, Duo Mobile Passcodes, Hardware Tokens etc to login to your Duo-protected integrations.
- resolved Aug 06, 2025, 08:06 AM UTC
The issue affecting SMS delivery to US phone numbers has been resolved. Services are now fully operational.