When searching for repositories, prioritize those that use modern languages and have recent "commits." Here are the most reliable methods currently available: A. The Python + Twilio/Plivo Approach
Often built with C#, these tools run on Windows and typically require a phone or modem to be connected to the PC. Key Features to Look For Free (and Cheap) Mass Texting for Nonprofits - Whole Whale bulk+smssender+github+work