A cordless telephone or portable telephone is a telephone with a wireless set that communicates through a base station that is connected to a fixed telephone line that can be operated near its base station. A cordless telephone requires electricity to power the main base station. A cordless handset can be powered with a battery that is recharged by the base station. It generally takes a period of twelve to twenty-four hours to get the phone charged. Modern cordless telephone standards, like PHS and DECT have blended the once clear-cut line between cordless and mobile telephones by supporting cell handover with various advanced features like data-transfer and even, on a limited scale, international roaming. In these models, base stations are maintained by a commercial mobile network operator and users subscribe to the service.

George Sweigert, an amateur radio operator and inventor from Ohio is considered as the father of the cordless phone. Sweigert, a radio operator in World War II stationed at the South Pacific Islands developed the full duplex-concept for untrained personnel, to improve battlefield communications for senior commanders, which was the beginning of a revolution in the field of telecommunication.

Cordless phones became an ingredient part of communication in the beginning of the 1980's with a large number of manufacturers entering into the market.

It ended the monopoly of Bell System around 1984 that led to the commercial feasibility of cordless phones. After the breakup, users bought their own phones, usually cheaper ones. In the 1980’s, new companies entered the cordless-phone market namely V-Tech, Uniden, Philips and Panasonic.

Most cordless-phone makers do not specify the chemical nature of the batteries, but V-Tech has admitted using NiMH batteries in handsets and has offered replacement batteries.