Microcontroller Based PBX System with 3 Extensions has 1 trunk line and finds an application in homes and offices. Microcontroller Based PBX System with 3 Extensions is manufactured by Matrix Telecom Private Limited which is an ISO 9001 certified company. Matrix Telecom Private Limited also manufactures various types of cutting-edge telecom products like IP-PBX, universal gateways, VoIP gateways and terminals, GSM FCTs, GSM gateways, access control, time-attendance systems and fire alarm systems. The Microcontroller Based PBX System with 3 Extensions, Model Proton 103, is based on state-of-the-art surface mount technology [SMT] ensuring high reliability. This System has flash timer for call hold and power down mode day/night modes. This System has 4 ports and power consumption of 10W. This System has dimension of 17 X 23.5 X 6cm and weight of 2Kg.