ESI offers a complete line of easy-to-use telephone systems. There is even a verbal help menu button on each phone. The smallest has 4 lines, 10 phones, and 4 voice mail ports. The largest has 240 lines, 816 phones, 128 voice mail ports. Features include: Caller ID, ACD, Music-On-Hold, VOIP, Unified Messaging, Call Reports, & Bluetooth Compatability. We offer all with a five year warranty.