QA Tester for SMS service of my mobile app

We are looking for testers in US to try a new SMS service and provide feedback. Our service helps people learn how to use my app. We’re looking for ways to improve the service. Testing will take 1 week. Testers will receive SMS messages each day. Testers will be asked to reply to our SMS messages. The service is in US. We are looking for native US speakers only. Job is a contract requiring no more than 5 hours over the course 1 week and pays a fixed contract of $100.