Load test - SMS reminder sender (staging, provider sandbox)
Date: 8 Oct

Ramp: 200 -> 1,400 messages/min over 30 min

Peak sustained rate:     1,200 messages/min for 20 min
p95 send latency:        2.1 s
Error rate at 1,200/min: 0.4%

Above 1,250 messages/min the provider returned HTTP 429 (rate limited) on 31% of sends.
Retries were not enabled for this run.