Twilio Verify: Resiliency for uninterrupted authentication

Twilio Verify: Resiliency for uninterrupted authentication

Understanding the importance of resiliency

The reliability of authentication services is not just a convenience—it's a necessity. No service can promise 100% uptime, and different use cases demand varying levels of reliability. While marketing and notification messages might tolerate some delays, authentication methods like OTP verification leave little room for error. The consequences are immediate when an end user cannot access their account or verify their identity.

Twilio Verify addresses these mission critical scenarios with intelligent failover mechanisms, designed to maintain service reliability when needed. Verify monitors vast amounts of data in real-time, detecting network degradation, outages, and other issues. By dynamically routing traffic through multiple global carriers and networks, Verify maximizes delivery rates, helping businesses safeguard their user experience even during disruptions.

As verification traffic scales, resiliency depends not only on carrier redundancy, but also on the ability to react when a specific sender or route begins to underperform.

Twilio Verify in action: real-world resilience

Case Study 1: Addressing Delivery Delays with Enhanced Monitoring

On June 5th, 2024, over a 2.5-hour period, Twilio customers experienced message delivery delays due to an incident with a major US carrier. During this time, some messages were delayed by up to 31 minutes. Twilio Verify was successful in detecting the issue through its conversion rate monitoring system. This proactive detection helped maintain normal conversion rates despite the incident. In contrast, messages sent through customer-owned short codes experienced a conversion rate drop of up to -37%¹.

Case Study 2: Short Code Failover Success

On May 24-25, 2023, a subset of Twilio US Short Codes experienced a significant outage, which completely disrupted services for Twilio Programmable Messaging customers using those shortcodes. In contrast, thanks to its managed number pool and automatic failover systems, Verify rerouted traffic away from affected shortcodes. Although the OTP Verification Success Rate dropped from 86% to 56% during the incident¹, this proactive failover avoided a total outage, ensuring continued verification processes for users.

Case Study 3: Handling Cross-Platform API Errors

On February 26, 2021, a disruption within one of Twilio’s internal services had a widespread impact, causing 72% of API requests to fail for Twilio Programmable Messaging over a 2.25-hour period¹. However, Twilio Verify's robust infrastructure minimized the effect. Leveraging its built-in resilience features, including redundancy across different communication paths, Verify continued to deliver OTPs, limiting the disruption's impact and demonstrating its ability to adapt even during system-wide issues.

The technical edge: building end-to-end resiliency

Twilio’s approach to resiliency starts with infrastructure. Twilio has invested in global failover strategies designed to help ensure uptime, even in the face of regional disruptions. This includes using multiple providers, global SMS routing, and redundancy to protect message delivery.

Automatic sender fallback: adding more control to verification resiliency

Even the most robust verification systems remain vulnerable to the unpredictable nature of telecommunications networks. For OTP use cases, where delivery speed directly affects conversion, short-lived sender or carrier issues can have an immediate impact.

To reduce that risk, Twilio introduced Automatic Sender Fallback in 2025. This capability monitors the performance of Verify’s US platform senders and dynamically reroutes traffic to the highest-performing available path when degradation is detected.

Twilio is now expanding that capability to give businesses more direct control over how messaging resiliency is managed.

Bring your own messaging sender into the fallback pool

One of the most significant updates is the ability to include your own Messaging Services and preferred senders in the fallback pool. Instead of relying only on platform-owned sender assets, businesses can now apply the same resiliency logic to the senders they already use and trust.

If a primary sender begins to underperform, Verify can automatically shift traffic to another sender in the pool to help maintain delivery performance and protect conversion.

Granular control with configurable thresholds

Resiliency should not be a black box. With this update, customers can define the thresholds that trigger fallback behavior based on their own operational needs. They can also set the priority order of senders in the fallback sequence, determining which routes are attempted first and which serve as secondary or tertiary safety nets.

This allows routing strategies to align more closely with business priorities, whether the goal is maximizing conversion, honoring sender preferences, controlling cost, or meeting internal policy requirements.

The value of seamless recovery

For high-volume verification use cases in the US, this creates a more adaptive and self-healing messaging layer. Verify continuously measures the conversion performance of the primary sender, shifts traffic when it drops below the configured threshold, and can automatically return traffic once performance recovers.

The result is a feedback loop that helps stabilize verification conversion rates without requiring teams to manually intervene during every sender or carrier disruption.

But the journey to resiliency is also a partnership. Twilio provides best practices and comprehensive documentation to help businesses build additional layers of protection into their applications. Whether handling network failures, sender degradation, or service interruptions, Twilio helps customers create stronger, more resilient systems.

Twilio Verify

Twilio Verify is more than just an authentication tool—it’s a business safeguard. With its intelligent failover capabilities and resilient infrastructure, Twilio Verify ensures that even when outages or disruptions occur, your end user verification flows continue without fail. Verify provides the peace of mind that your business operations remain uninterrupted.

What’s Next?

Interested to know more about Twilio Verify and SMS pumping fraud prevention? Check out the Twilio Verify API documentation.

Catie is a Principal Product Marketing Manager at Twilio where she works with the User Authentication & Identity Team on Verify and Lookup. Catie has worked with a variety of SaaS and tech companies across telecommunications and identity intelligence industries.

Abe Duarte-Rey is a Principal Product Manager at Twilio on the Verify team. Originally from Colombia, Abe's career began in software development and expanded to founding startups in the gig economy and fintech industries.

¹ Internal data