Can my SMS messages arrive in order?
Twilio cannot guarantee that SMS messages sent from your Twilio phone number will arrive in order. While we will send the SMS messages you pass to us in the order that you’ve queued them, the SMS messages are delivered individually with no association to each other. The order of delivery depends on the carrier.
To help your users understand the order of your messages, we recommend that you append a page reference following each message, for example 1/3, 2/3, 3/3.