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telephony

By Alexander S. Gillis

What is telephony?

Telephony is technology associated with interactive communication between two or more physically distant parties via the electronic transmission of data. Long associated with voice communication, telephony has evolved to also include text messaging, video calling, video conferencing, voicemail, call recording and faxing. Telephony provides an efficient and effective means of communication for individuals and businesses.

A telephonic exchange historically required the use of traditional fixed-line telephones, handheld devices containing both transmitters and receivers that connected to local exchange networks via physical wiring. Telephonic communication increasingly happens using modern computing and cellular technology, thus blurring the line between telephony and telecommunication. The definition of telephony and its scope have expanded accordingly.

Internet telephony lets users make calls over Internet Protocol (IP) networks at a much lower cost than over the traditional public switched telephone network (PSTN). Computer applications called softphones behave like legacy telephones but without the need for standalone devices. IP telephony software can reside on a variety of computing hosts, including PCs, smart desk phones, smart mobile phones and tablets.

How telephony works

How telephony works depends on the form of telephony implemented. For example:

Benefits of telephony

Telephony provides the following benefits:

Downsides of telephony

Some downsides associated with telephony, however, include the following:

History of telephony

The word telephony comes from the Greek root words for far -- tele -- and speak -- phone. In 1876, Alexander Graham Bell famously patented the telephone to electronically transmit human speech, building on the success of the telegraph system. A few days later, he spoke the first words ever communicated via telephone to his assistant, Thomas Watson, who was in the next room: "Mr. Watson, come here. I want to see you." The following year, he made the first distanced phone call in history -- from Salem, Mass., to Boston -- and founded the Bell Telephone Company, which would later become part of AT&T.

The earliest telephones came in pairs, with each line directly connecting just two locations. This was impractical, however, as users needed a separate wired device for each contact they wished to call. Soon, the invention of the telephone exchange enabled users to communicate with any other local party wired for service, with the help of a switchboard operator. Trunk lines connected individual telephone exchanges, enabling calls to take place over increasingly significant distances.

AT&T began planning a cross-country telephone line in 1908, eventually laying 3,400 miles of copper wiring from coast to coast. Engineers used innovative loading coils and vacuum tubes to amplify electrical signals as they made their way across the country.

Thirty-nine years after filing his patent, Bell inaugurated the transcontinental telephone service with a ceremonial call from New York to San Francisco. He repeated his now-famous words: "Mr. Watson, come here. I want to see you." Watson replied from California: "It will take me five days to get there now." President Woodrow Wilson and AT&T President Theodore Vail joined them on the call.

Other major milestones in the history of telephony include the following:

4 types of telephony systems for the enterprise

  1. Legacy, circuit-switched PBX. In traditional phone systems, on-premises private branch exchange (PBX) boxes act as in-house switching centers, connecting calls between internal devices directly and routing external calls to and from the PSTN via dedicated trunk lines. Human operators managed the earliest PBX systems but were eventually replaced by modern automated attendants.

    While expensive and complex -- and more or less obsolete -- legacy PBX systems have historically been most attractive in areas with unreliable network connectivity or electrical power. Some hard-wired phone lines continue to work even in the event of electrical outages.

  2. VoIP PBX. Similar to the traditional PBX, a VoIP or IP PBX essentially creates a private phone network within a business but does so via the internet or a private local area network rather than dedicated voice circuits.

    Because it doesn't require a separately wired network or rely on the PSTN -- with its long-distance charges -- internet telephony is significantly less expensive than legacy PBX systems. It also offers more geographic flexibility to users, as they can access softphone applications across their devices, rather than staying tethered to desk handsets.

    On-premises IP PBX telephony systems consist of software running on servers. An onsite IP PBX typically offers more sophisticated feature sets and greater reliability than a cloud-based VoIP service, but it's also more expensive and complex to deploy, manage and maintain.

  3. Hybrid PBX. Some organizations deploy a hybrid PBX model that uses both legacy and IP telephony technology -- whether for redundancy, cost savings or to enable a staged migration to VoIP. These environments use gateways to bridge VoIP and PSTN functionality.

    Alternatively, some use the term hybrid PBX to refer to a VoIP telephony system with both on-premises and cloud-hosted resources.

  4. Cloud VoIP. Cloud VoIP, also known as cloud telephony or cloud calling, is a VoIP service provided by a third party. By outsourcing its system, an enterprise can eliminate the need to provision, manage and maintain an onsite IP PBX, reducing infrastructure costs and increasing scalability. Features, functionality and controls tend to be less comprehensive than on-premises options, although many analysts expect that difference to shrink with time.

Key telephony use cases

There are a range of potential individual and business use cases for telephony technologies. For example, telephony is used for sending text messages, making voice calls, video calling, business conferences, leaving voicemails as well as sending faxes.

Other use cases of telephony systems include the following:

Telephony platforms and vendors

Today, organizations can choose from a plethora of on-premises and cloud-based VoIP telephony vendors, from major carriers to up-and-coming startups. These include the following examples:

Some example telephony services include the following:

IP telephony and VoIP are similar technologies. Learn more about each and the differences between them.

08 Nov 2023

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