The GB2™ Series, simply put, is our lowest cost multi-family digital audio-intercom system. The GB2™ series connects to two (2) non-polarized wires and can handle up to 256 apartment audio stations and up to four (4) door entry stations. While the GB2™ Series digital audio-intercom is designed primarily for use in multi-family (apartment house) or commercial office buildings, it can also be used in residential applications, in "villa mode". The GB2™ Series features a choice of the NHEA GB2 (open-voice) or the T-562 (handset) audio-intercom stations.