Telecommunication

The public switched telephone network (PSTN) is the concatenation of the world's public circuit-switched telephone networks, in much the same way that the Internet is the concatenation of the world's public IP-based packet-switched networks. Originally a network of fixed-line analog telephone systems, the PSTN is now almost entirely digital, and now includes mobile as well as fixed telephones.

A teleprinter (teletypewriter, teletype or TTY) is a now largely obsolete electro-mechanical typewriter which can be used to communicate typed messages from point to point through a simple electrical communications channel.

Developer(s) Skype Limited
Initial release August 2003 (2003-08)
Stable release 5.3.0.111 (Windows)
5.1.0.922 (Mac OS X)
2.2.0.25 (Linux) (April 20, 2011; 4 days ago (2011-04-20) (Windows)
April 14, 2011; 10 days ago (2011-04-14) (Mac OS X)
April 6, 2011; 18 days ago (2011-04-06) (Linux)) [+/−]
Preview release [+/−]
Written in Embarcadero Delphi / Objective-C (Mac OS X/iPhone) / C++ with Qt4 (Linux)
Operating system Cross-platform
Available in Multilingual

Almost in parallel with Germany's telex system, Bell Labs in the 1930s decided to go telex one better, and began developing a similar service (with pulse dialing and all!) called "Teletype Wide-area eXchange" (TWX).

Computer telephony integration, also referred to as CTI, is technology that allows interactions on a telephone and a computer to be integrated or co-ordinated.

The following functions can be implemented using CTI.

• Calling Line Information Display (Caller's Number, Number Called, IVR Options)

Fax (short for facsimile or telefacsimile) is a telecommunications technology used to transfer copies of documents, especially using affordable devices operating over the telephone network. Such faxes became affordable and very popular in the 1980s.