We use Twilio as our SMS provider. 

Merchants who have setup SMS Alerts will receive SMS Alert messages from different originating phone #s.

  1. 833-903-2535
  2. 833-698-0480
  3. 833-442-0228
  4. 833-440-0885
  5. 833-430-0302
  6. 833-409-1110

"In the United States, it’s typically recommended that you add one long code number for every 200 unique recipients per day (because long codes are intended for person-to-person traffic). For example, if your SMS technical support number typically exchanges messages with 1,000 people a day, you should add 5 phone numbers to your Messaging Service."
Ref: https://www.twilio.com/docs/sms/services/copilot-best-practices