Built from the ground up specifically for small and medium-sized businesses, YEASTAR Mypbx OFFICE TELEPHONE SYSTEM delivers the communications capabilities big businesses are used with the elegant simplicity and ease of use small businesses consider a must have. This best-of-both-worlds small BUSINESS PHONE SYSTEM helps growing enterprises differentiate themselves from competitors through enhanced employee productivity, lower costs and improved customer service. The New Yeastar S Series PBX Consist of different models to full fill all organization telecom requirements. The S Series Models are S20, S50, S100, and S300.