2.4GHz ISM BAND WIFI and Bluetooth Intercom systems works in world open band. It can dial and communicate between wireless intercoms up to 1000 extensions. You need just plug the wireless intercom to any of your 90 - 250V outlet within the range limit. Each of the intercoms will have dialling facility for numbers and also you can change/program the numbers as you require. This wireless intercom uses Encrypted Adaptive Frequency Hopping Technology. Hence, it has super Anti-Jamming capability and also nobody can tap into your conversation. It is also possible for 250 people to communicate at a time without any cross mingling. It has a range of about 300-500m in open area, without any cabling. Broadcasting facility also available for school /college application.