Dartmouth's phone system works with Poly's Trio 8300, 8500 and 8800 for conference phones. The 8300 is intended for small conference rooms; the 8500 is intended for rooms no larger than 28 feet (a microphone range of 14 feet in each direction from the Trio); the 8800 for larger rooms with a microphone range of up to 20 feet in each direction from the Trio. Extension microphones are available for spaces that are even larger.