It installs using a single pair of wire for (power, control, signaling & voice). Add on components install on same single pair of wire. If you wish to use your phones handsets as intercoms also add module model DP28IM. Mounts directly on any Surface.Installs using single pair of wire. The distance from Door Box to the Controller may be extended up to 4,000 feet using Cat5E cable. Distinctive ring for each entryway. The item "DoorBell Fon Model DBF-DP28IT (Ivory)" is in sale since Tuesday, October 10, 2017. This item is in the category "Home & Garden\Home Improvement\Home Security\Door Entry Systems & Intercoms". The seller is "allsecurityequipmentcom" and is located in Miami, Florida. This item can be shipped to United States, Canada, United Kingdom, Denmark, Romania, Slovakia, Bulgaria, Czech republic, Finland, Hungary, Latvia, Lithuania, Malta, Estonia, Australia, Greece, Portugal, Cyprus, Slovenia, Japan, China, Sweden, South Korea, Indonesia, Taiwan, South africa, Thailand, Belgium, France, Hong Kong, Ireland, Netherlands, Poland, Spain, Italy, Germany, Austria, Bahamas, Israel, Mexico, New Zealand, Philippines, Singapore, Switzerland, Norway, Croatia, Brazil, Chile, Colombia, Antigua and barbuda, Aruba, Belize, Dominica, Grenada, Saint kitts and nevis, Saint lucia, Turks and caicos islands, Barbados, Bangladesh, Bermuda, Brunei darussalam, Bolivia, Ecuador, Egypt, French guiana, Guernsey, Gibraltar, Guadeloupe, Iceland, Jersey, Jordan, Cambodia, Cayman islands, Liechtenstein, Sri lanka, Luxembourg, Monaco, Macao, Martinique, Maldives, Nicaragua, Oman, Peru, Pakistan, Paraguay, Reunion, Viet nam, Uruguay, Russian federation, Montserrat.