This document describes a mobile English tutoring service called TELLA that provides personalized 1-on-1 tutoring via text and voice chat with native English tutors for 30 minutes per day. It analyzes user data to track progress and customize tutoring and self-study content. The service aims to offer affordable English instruction through a technology-driven, personalized curriculum delivered by an online platform. It plans to launch an app, continuously upgrade the data analysis system and app functions, and expand globally within two years on an investment of $200,000.