Annabelle is at The Museum of Natural History.
A telephone , or phone , is a telecommunications device that permits two or more users to conduct a conversation when they are too far apart to be heard directly .. A telephone converts sound , typically and most efficiently the human voice , into electronic signals suitable for transmission via cables or other transmission media over long distances , and replays such signals simultaneously in audible form to its user .. sound. sound. human voice. human voice. transmission. transmitter. In 1876 , Scottish emigrant Alexander Graham Bell was the first to be granted a United States patent for a device that produced clearly intelligible replication of the human voice .. human voice. human voice. Alexander Graham Bell. Alexander Graham Bell. This instrument was further developed by many others .. The telephone was the first device in history that enabled people to talk directly with each other across large distances .. Telephones rapidly became indispensable to businesses , government , and households , and are today some of the most widely used small appliances .. The essential elements of a telephone are a microphone -LRB- transmitter -RRB- to speak into and an earphone -LRB- receiver -RRB- which reproduces the voice in a distant location .. microphone. microphone. earphone. earphone. In addition , most telephones contain a ringer which produces a sound to announce an incoming telephone call , and a dial or keypad used to enter a telephone number when initiating a call to another telephone .. sound. sound. telephone number. telephone number. Until approximately the 1970s most telephones used a rotary dial , which was superseded by the modern DTMF push-button dial , first introduced to the public by AT&T in 1963 .. rotary dial. rotary dial. DTMF. Dual-tone multi-frequency signaling. AT&T. AT&T. The receiver and transmitter are usually built into a handset which is held up to the ear and mouth during conversation .. handset. handset. The dial may be located either on the handset , or on a base unit to which the handset is connected .. handset. handset. The transmitter converts the sound waves to electrical signals which are sent through the telephone network to the receiving phone .. sound. sound. electrical signals. Signal ( information theory ). The receiving telephone converts the signals into audible sound in the receiver , or sometimes a loudspeaker .. sound. sound. loudspeaker. loudspeaker. Telephones permit duplex communication , meaning they allow the people on both ends to talk simultaneously .. duplex communication. Duplex ( telecommunications ). The first telephones were directly connected to each other from one customer 's office or residence to another customer 's location .. Being impractical beyond just a few customers , these systems were quickly replaced by manually operated centrally located switchboards .. This gave rise to landline telephone service in which each telephone is connected by a pair of dedicated wires to a local central office switching system , which developed into fully automated systems starting in the early 1900s .. landline. landline. For greater mobility , various radio systems were developed for transmission between mobile stations on ships and automobiles in the middle 20th century .. transmission. transmitter. Hand-held mobile phone -RSB- s was introduced for personal service starting in 1973 .. mobile phone. mobile phone. By the late 1970s several mobile telephone networks operated around the world .. In 1983 , the Advanced Mobile Phone System -LRB- AMPS -RRB- was launched , offering a standardized technology providing portability for users far beyond the personal residence or office .. Advanced Mobile Phone System. Advanced Mobile Phone System. These analog cellular system evolved into digital networks with better security , greater capacity , better regional coverage , and lower cost .. The public switched telephone network , with its hierarchical system of many switching centers , interconnects telephones around the world for communication with each other .. public switched telephone network. public switched telephone network. With the standardized international numbering system , E. 164 , each telephone line has an identifying telephone number , that may be called from any authorized telephone on the network .. telephone number. telephone number. Although originally designed for simple voice communications , convergence has enabled most modern cell phones to have many additional capabilities .. convergence. Technological convergence#Cell phone convergence. They may be able to record spoken messages , send and receive text messages , take and display photographs or video , play music or games , surf the Internet , do road navigation or immerse the user in virtual reality .. record spoken messages. Answering machine. text messages. Text messaging. take and display photographs. Camera phone. video. Videotelephony. games. video game. surf the Internet. Mobile browser. road navigation. turn-by-turn navigation. virtual reality. virtual reality. Since 1999 , the trend for mobile phones is smartphones that integrate all mobile communication and computing needs .