We are sending SMS to Twilio through a generic http operation in an Ensemble Production. Works well. We wrote a simple Process that catches HTTP 429 errors (their API documentation has a requirement about this).

I have this very error every day. Also running 2022.1

You could have a 0 day Ens.Util.Purge task running every 5 mins and clearing the production messages. That way you could use only built-in components such as the hl7 tcp service and hl7 file operation