[RESOLVED]
Requests to Safaricom numbers are intermittently timing out, the error thrown is 504 Gateway Timeout.
This is due to TCP connection errors on the Safaricom SMS Gateways resulting in requests submitted to them timing out.
We recommend adding the enqueue flag in your requests to the API so that instead of directly sending to the Safaricom Gateways we queue the requests and send them in smaller batches to the Safaricom SMS Gateway.