Mechanical censorship is a one of the emerging technologies in field of sensors and networks used in telecommunications. The major use of this technology is to check for the validity of a voice or data transfer between two entities in a network. It involves the development of software which gives warning sounds and lights when certain in appropriate words are used or given as an input to the system during a call. It includes a variety of counter technologies to screen calls and faxes. It involves encryption and decryption of data also which adds to the security of the data transfer between the entities. Cellular phones use digital signals which are very difficult to intercept. There are phones in Europe which produce a warning light that goes on if someone answers the call by picking an extension phone and some simply remain as dead. There is also a blocking option in the Caller Id of the phone to mask the number of the user. Some fax machines also maintain records of messages when a situation of insufficient of paper arrives. There are automated dialers which are used to verify the identity of the receiver before they start to communicate with others.