Phonomax Intercom System is designed using Surface Mount Technology components eliminating bulk old component blocks and transformers resulting to a more reliable and compact product. More stress is given on protection for each card as well on extension circuits, which enhances life of the product drastically. The line cards are equipped with Subscriber line interface Circuit (SLIC)based, which gives better sound clarity without any crosstalk and gives better life to Telephone Instruments attached to it as the SLIC's complies norms for telephone interface. The SLIC are more stable and well protected.