Sending invitations by SMS / Text Message through EventCreate is not supported due to spam laws and restrictions.
If you need to invite people by text message, you should invite guests via personal phone by sharing your event URL. To find your URL, go into your Event Dashboard > Setup > Website > URL.
Once a guest has registered for your event and granted permission to be contacted by text, you can send event reminders and updates through EventCreate!
You can send follow-up or reminder texts through EventCreate on any plan as an optional add-on (attendee permission required). To enable it, visit your Billing page.