Marketing cloud - how to send a transactional SMS via API

Question

I want to send an SMS after the user places an order.

I found this article: https://developer.salesforce.com/docs/atlas.en-us.noversion.mc-apis.meta/mc-apis/transactional-messaging-get-started.htm.

But, there are some things I don't understand:

1. Do I need to create one "definition" or create a "definition" for each send?
2. In the documentation of sending the SMS, I see this object:

"subscriptions": {
       "resubscribe": true
}

What is it used for? After all, we send a transactional SMS.

Answer 1

1. You only need to create one definition per message template. Each send would then use that definition. So you're not creating a new definition for every single contact.

2. I believe the example for transactional SMS is using a payload for the generic SMS triggered send as the parameter isn't listed in the documentation. It shouldn't be required for transactional SMS. But to answer your question it will resubscribe a contact as you're sending the message as opposed to having the contact manually opt-in to the keyword.