Multi-Region Failover for OTP APIs

For India-first apps, the most useful failover is provider-level, not region-level. This guide covers the layered approach.

Failover Levels

1. Provider redundancy (primary + secondary).
2. Operator-route redundancy within a provider.
3. Channel redundancy (SMS → voice → WhatsApp).
4. Region redundancy (only if you serve multiple geos).

Provider Redundancy

• Two providers under feature flag.
• Health-check based switch.
• Periodic small-fraction shadow traffic to keep both warm.

Health Checks

• Track provider DLR success rate per minute.
• Drop below 90% → flip to secondary.
• 30-min cool-down before re-switching.

DNS / Anycast

Provider already runs DNS-level redundancy. You don’t need Anycast in front of an OTP API call.

Cost Trade-off

• Multi-provider doubles operational complexity.
• Most teams start with single multi-route provider, add second only at SLA-driven scale.

FAQ

StartMessaging handles operator-route failover internally; layer a second provider above only when SLA demands.