# All Deployments: Duo Phone Call and SMS Delivery Failure

- Provider: [Duo Security](https://down.guide/duo)
- Level: confirmed
- Impact: Partial outage
- lasted 2h 38m
- started 2025-10-20 08:28 UTC
- Phone Call Delivery, Phone Call Delivery, Phone Call Delivery +155
- id: DWN-27382d2d25
- Official page: https://stspg.io/6n75c2qyq7lj

## Updates from Duo Security
### 2025-10-20 08:29 UTC: investigating
We are currently investigating an issue causing phone call and SMS delivery authentication failures on all of our deployments and are working to correct the issue as soon as possible.
Please check back here or subscribe to updates for any changes.

### 2025-10-20 08:52 UTC: identified
We've identified the cause of degraded Phone Authentication and SMS delivery failures. 
Our providers have acknowledged an upstream issue and are working on a resolution. 
This may affect users relying on phone calls or SMS for authentication across all deployments and we suggest using alternate means of MFA such as Duo Push if possible.
Our team is working on mitigation steps and will continue to provide updates as progress is made.

### 2025-10-20 11:06 UTC: resolved
The issue affecting phone-based authentication and SMS delivery has now been resolved. System performance has remained stable, and all services are operating as expected across deployments.
We will continue to monitor for any anomalies, but no further impact is anticipated at this time.

---
down.guide reads providers' official status pages every minute and adds its own evidence, always labeled. Free, no account. Agents: MCP at https://down.guide/mcp, REST at https://down.guide/api/v1, feeds at https://down.guide/feed. Built by Sazabi (https://sazabi.com/?utm_source=down-guide&utm_medium=markdown).