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 * "Phone Call" redirects here. For the OmPuff album, see Phone Call (album).

A telephone call is a connection over a telephone network between the calling party and the called party. Telephone calls are a vital part of society and telecommunication. There are approximately 10 billion telephone calls made daily worldwide.

=History of the telephone call= Historically telephone calls are placed between two wired telephones, and routed through a telephone network switchboard by an operator. The first telephone call was made on March 10, 1876 by Alexander Graham Bell. Bell demonstrated his ability to "talk with electricity" by transmitting a call to his assistant, Thomas Watson. The first words transmitted were "Mr Watson, come here. I want to see you." This event has been called Bell's "greatest success", as it demonstrated the first successful use of the telephone. A non-powered telephone would have a hand crank to ring the operator, and ask to be connected to a certain called party. These operators began as young teenage boys who had a reputation of being rude to customers. After the firing of young boys call centers were employees almost exclusively by women until the 1970s. The experience of making a call has drastically changed from Edison's first call to present day, and the beginning of this started in 1891, with the invention of the rotary phone.

Rotary dial calling
The invention of the rotary dial phone made it unnecessary to speak to the operator during every call, as the requested number was automatically sent to the call center via a loop disconnect, or pulse dialing signal. This is achieved with electrical pulses sent through the DC phone line. The first phones to have dialers used keys, but this was quickly thrown out and the popular rotary dial became standard on phones, up until the touch tone era. These pulses eventually lead to automatic switchboards and faster phone calls, with switchboards and operators only necessary when calling out of a specific network.

As the telephone network grew in size exponentially in the 1920's and 30's, long distance calling became possible. To complete such a call required your telephone signal to pass through multiple switchboards and call centers, until eventually coming to a hub connected to an inter-continental or international circuit. At first this was not an instantaneous process and required many operator transfers, who would physically plug a front line in to pass the signal on.

Touch-tone calling
The next major change to the experience of making a telephone call was the invention of the push-button telephone, commonly called a "touch-tone" telephone. The first touch-tone system was installed in Baltimore, Maryland in 1941. These were not a commercial hit until decades later, and were huge at the 1962 Seattle World's Fair. A push button phone uses dual-tone multi-frequency signaling to instantly dial a number. This meant quicker dial times as the user no longer had to wait for pulses to dial out from the telephone. This dialing system became the standard for landline service, and still is to this day.

The telephone network continued to exponentially grow in size in the later 20th century, and as calling became fully automated with very seldom use of an operator, the called party could be connected to and reached quicker than ever. An operator could still be reached on many networks by dialing “0”, frequently labeled the operator key.

Digital calling
As the internet became more popular during the late 1990's and into the 2000's, many landline subscriber's converted from making receiving calls from a standard telephone line to voice over internet protocol, where a broadband connection is used to transmit the phone call completely digitally. This has became a popular option as it is frequently bundled with broadband internet and cable subscriptions, at a lower cost the the user than a standard phone company.

Echo canceling
While call quality has not specifically increased since digital calling became possible, one advancement in telephone call technology is the invention of echo canceling and active noise canceling. Echo canceling is made possible by blocking out the frequencies being produced in the speaker from being transmitted while picked up at the microphone. This is necessary on applications such as speakerphone, to prevent feedback and echo to the calling party. Similar to echo canceling is noise canceling, where an additional microphone on the telephone picks up background noises, and by sending out the opposite signal, blocks the background noise from being heard by both parties. This makes it much easier to hear a phone call while in a constant-noise environment.

Mobile telephones
Today, when a phone call is made it is most likely to be made by a mobile or cellular phone.. When calling on a mobile phone, data is transferred wirelessly in a duplex signal to a cellphone tower, and either routed through the carrier's own network when calling a cellphone under the same carrier, or through a landline network depending on the respective party called. While historically cell phone calls used more simple frequencies similar to a CB radio, meaning only a certain amount of calls could be connected at one time in a given area, advanced cellphone frequency technology such as 3G/4G GSM and TDMA frequencies means that a lot of cellphone calls are made in a similar fashion to VoIP. This makes for faster and clearer connections, using digital encoding for voice transmissions. As mobile phones become more popular and now includes the age of the smartphone, less actual telephone calls are being made on these devices, while there is an increasing amount of SMS text messages and instant messaging vis social media.

=Information transmission=

When typically discussed, a telephone call refers to a voice connection between two telephones, whether it be [landline] or [mobile] phones. The telephone network has been developed to send many different types of data however, and calls between two devices can carry facsimile or other data as well, such as DSL or dial-up internet. These data transmissions are similar to voice connections yet use much higher frequencies to transmit information.

A telephone call may carry ordinary voice transmission using a telephone, data transmission when the calling party and called party are using modems, or facsimile transmission when they are using fax machines. The call may use land line, mobile phone, satellite phone or any combination thereof. Where a telephone call has more than one called party it is referred to as a conference call. When two or more users of the network are sharing the same physical line, it is called a party line or Rural phone line.

If the caller's wireline phone is directly connected to the calling party, when the caller takes their telephone off-hook, the calling party's phone will ring. This is called a hot line or ringdown. Otherwise, the calling party is usually given a tone to indicate they should begin dialing the desired number. In some (now very rare) cases, the calling party cannot dial calls directly, and is connected to an operator who places the call for them.

Calls may be placed through a public network (such as the Public Switched Telephone Network) provided by a commercial telephone company or a private network called a PBX. In most cases a private network is connected to the public network in order to allow PBX users to dial the outside world. Incoming calls to a private network arrive at the PBX in two ways: either directly to a users phone using a DDI number or indirectly via a receptionist who will answer the call first and then manually put the caller through to the desired user on the PBX.

Most telephone calls through the PSTN are set up using ISUP signalling messages or one of its variants between telephone exchanges to establish the end to end connection. Calls through PBX networks are set up using QSIG, DPNSS or variants.

Sound powered phone
Sound powered telephones are phones that create their own power. This changes the experience of the calling and called part significantly compared to a digital transmission. The phone uses an electro-mechanical transducer on a single wire pair and zero need for an outside battery source. With the produced sound pressure the transmitter creates a [voltage] that goes to the receiver which changes it back into sound and can be heard on the other end of the line. This kind of phone is heavily used for temporary phones in construction sites as well as area where there is a large fire hazard as it operates at a very low voltage and is not a fire hazard. Sound powered phones are also used in case of an emergency power loss in a facility or ship. While using a sound powered telephone, communication can be much more difficult than on a powered phone, as one needs to annunciate very clearly and precisely in order to create an understandable conversation.



Satellite Phone
Another unique form of a telephone call's information transmission is through a satellite phone. Although cellphones have a range that is far greater than a land line telephone they still cannot reach places where a cellular tower isn't close by. The ability to make a call anywhere on the globe was first made available by Motorola in 1997 when they launched their fleet of 66 satellites into orbit which spread evenly over the globe and transmit to 13 different ground stations around the world so that call can be made through a satellite phone, this project was called the Iridium satellite constellation and was the first of its kind. Placing a call from a satellite phone is unlike using any other telephone, because you can connect to anywhere in the world from very remote locations. This makes satellite phones extremely valuable in certain situations such as being out at sea, or in other remote locations where there is no other means of outside communication.

Though Iridium was at the forefront of satellite communications it simply couldn't last because of a lack of demand by the population. Ten months after its launch Iridium was bankrupt. The price of their goods and services was just too high. With handsets that were being sold for $1,300.00 and a price of $7.00 per minute of communications via satellite the general population just didn't want to spend that kind of money. This lack of customer base couldn't make up the five billion dollars that was spent to get Iridium to a functioning state. Today, satellite phones are much more affordable. =Costs= In most countries, local calls dialed domestically and directly by a telephone subscriber in Canada, the United States, Hong Kong, United Kingdom, Ireland or New Zealand are included in a baseline telephone subscription. In most other areas, all telephone calls are charged a fee for the connection. Fees depend on the provider of the service, the type of service being used (a call placed from a landline or wired telephone will have one rate, and a call placed from a mobile telephone will have a different rate) and the distance between the calling and the called parties. In most circumstances, the calling party pays this fee. However, in some circumstances such as a reverse charge or collect call, the called party pays the cost of the call. In some circumstances, the caller pays a flat rate charge for the telephone connection and does not pay any additional charge for all calls made. Telecommunication liberalization has been established in several countries to allows customers to keep their local phone provider and use an alternate provider for a certain call in order to save money. Certain calls, such as a satellite call or a call out of country will cost much more than a domestic or long distance call. These calls are typically billed at a minute or hourly fee.

Numbers including the 800, 888, 866 and similar are toll-free numbers. In this case, the recipient of the call (the called party) pays the entire cost of the call. Whether these calls are made on a payphone, landline or cellular phone. These numbers are frequently used for company connections, or customer service.

Placing a call
A typical phone call using a traditional phone is placed by picking the phone handset up off the base and holding the handset so that the hearing end is next to the user's ear and the speaking end is within range of the mouth. The caller would then rotary dial or press buttons for the phone numbers needed to complete the call.

In addition to the traditional method of placing a telephone call, new technologies allow different methods for initiating a telephone call, such as voice dialing. Voice over IP technology allows calls to be made through a PC, using a service like Skype. Other services, such as toll-free dial-around enable callers to initiate a telephone call through a third party without exchanging phone numbers.

The use of headsets is becoming more common for placing or receiving a call. Headsets can either come with a cord or be wireless.

A special number can be dialed for operator assistance, which may be different for local vs. long-distance or international calls.

Tones
Preceding, during, and after a traditional telephone call is placed, certain tones signify the progress and status of the telephone call:
 * a dial tone signifying that the system is ready to accept a telephone number and connect the call
 * either:
 * a ringing tone signifying that the calling party has yet to answer the telephone
 * a busy signal (or engaged tone) signifying that the calling party's telephone is being used in a telephone call to another person (or is "off the hook" though no number has been dialled, i.e. the customer does not want to be disturbed)
 * a fast busy signal (also called reorder tone or overflow busy tone) signifying that there is congestion in the telephone network, or possibly that the calling subscriber has delayed too long in dialling all the necessary digits. The fast busy signal is generally twice as fast as the normal busy signal.
 * status tones such as STD notification tones (to inform the caller that the telephone call is being trunk dialled at a greater cost to the calling party), minute minder beeps (to inform the caller of the relative duration of the telephone call on calls that are charged on a time basis), and others
 * a tone (sometimes the busy signal, often the dial tone) to signify that the called party has hung up.
 * tones used by earlier inband telephone switching systems were simulated by a Red box or a blue box used by "phone phreaks" to illegally make or receive free trunk/toll calls.
 * off-hook tone if the phone has been picked up but no number dialed for an extended period of time

Cell phones generally do not use dial tones, because the technology used to transmit the dialed number is different from a landline.

Unwanted calls
Unsolicited telephone calls are a modern nuisance. Common kinds of unwanted calls include prank calls, telemarketing calls, and obscene phone calls.

Caller ID provides some protection against unwanted calls, but can still be turned off by the calling party. Even where end-user Caller ID is not available, calls are still logged, both in billing records at the originating telco and via automatic number identification, so the perpetrator's phone number can still be discovered in many cases. However, this does not provide complete protection: harassers can use payphones, in some cases, automatic number identification itself can be spoofed or blocked, and mobile telephone abusers can (at some cost) use "throwaway" phones or SIMs. In the United States, the FCC prohibits all telemarketing to wireless phones (mobile phones), and if a US telephone subscriber registers on the National Do Not Call Registry telemarking calls to the registrar's number become unlawful.

Users
While a majority of people placing a telephone call are doing so simply for means of verbal communication, there are a select group of users who chose to use the telephone system for much different purposes. A “Phone Phreak” is a person who is obsessively interested in learning about, exploring, or playing with the telephone network also known as Phreaking. This practice of of playing with the telephone network was first started in 1955 by a man named David Condon who created a specialized whistle that when blown into the mouthpiece of the phone would ring forward to whoever just hung up the phone. Condon used this special whistle to make free long distance calls on pay phones.

The next man to become what would be called a “Phone Phreak” was Ralph Barclay. Barclay was a freshman at Washington State University, and it was there he created what would come do be known as the [blue box]. The blue box was a creation that allowed Barclay to mimic the signals that operators used to transfer calls so that he could place calls to anywhere in the country and some foreign countries for no charge.

The group of “Phone Phreak”’s that became the most well known was a group of students from Harvard and MIT. Charlie Pyne, Tony Lauck, Ed Ross, and Paul Heckel the latter being the only one from MIT and the rest were Harvard students. These students spent their hours sending signals out and repeating various beeps to catalog where various relay stations were and how to connect to as many different locations as possible, even coming across military bases. Though their endeavor was quickly brought to a halt once a man named Ernie Reid took the work of the four men to the phone company to have charges pressed. However, the FBI was also doing investigations of its own as they believe the group was part of a spy ring to get information from the military bases that they had made contact with. However, after weeks of further investigating the charges had been dropped as there was no clear evidence of criminal intent.

Patents

 * Rabinow, J., -- "Telephone call indicator"—November 12, 1957
 * Cooper, M., -- "Radio telephone system" -October 17, 1973
 * Aldous, A., -- "Voice over IP protocol based speech system"-June 19, 2000