It works just like an ordinary mobile phone but do not require any SIM card or subscription or rental. It also does not require any mobile tower / central exchange / PBX box / central box. But it will simply work as a private mobile network. You can dial and communicate between mobile handset up to 1000 extensions. Each of the handset will have dialling facility for numbers and also you can change/program the numbers as you require. This mobile handset model wireless intercom uses the Encrypted Adaptive Frequency Hopping Technology. Hence, it has a 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 500m~3000m without any cabling.