An analog telephone adapter (ATA) is a device for connecting traditional analog telephones, fax machines, and similar customer-premises devices to a digital telephone system or a

voice over IP Voice over Internet Protocol (VoIP), also called IP telephony, is a method and group of technologies for the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet. The terms Internet t ...

telephony network. An ATA is often built into a small enclosure with an internal or external power adapter, an

Ethernet Ethernet () is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 1 ...

port, one or more

foreign exchange station Foreign exchange service (FX) is an access service in a telecommunications network in which a telephone in a given exchange area is connected, via a private line, as opposed to a switched line, to a telephone exchange or central office in another e ...

(FXS) telephone ports. Such devices may also have a

foreign exchange office Foreign exchange service (FX) is an access service in a telecommunications network in which a telephone in a given exchange area is connected, via a private line, as opposed to a switched line, to a telephone exchange or central office in another e ...

(FXO) interface for providing alternative access to traditional landline telephone service. The ATA provides dial tone, Ringing Generator, DC power, caller ID data and other standard telephone

line signaling Line signaling is a class of telecommunications signaling protocols. Line signaling is responsible for off-hook, ringing signal, answer, ground start, on-hook unidirectional supervision messaging in each direction from calling party to called p ...

(known collectively as

BORSCHT Borscht () is a sour soup common in Eastern Europe and Northern Asia. In English, the word "borscht" is most often associated with the soup's variant of Ukrainian origin, made with red beetroots as one of the main ingredients, which g ...

) to the telephone connected to a modular jack. The digital interface of the ATA typically consists of an Ethernet port to connect to an Internet Protocol (IP) network, but may also be a USB port for connecting the device to a personal computer. Using such an ATA, it is possible to connect a conventional telephone to a remote VoIP server. The ATA communicates with the server using a protocol such as

H.323 H.323 is a recommendation from the ITU Telecommunication Standardization Sector (ITU-T) that defines the protocols to provide audio-visual communication sessions on any packet network. The H.323 standard addresses call signaling and control, mu ...

, SIP, MGCP, SCCP or

IAX Inter-Asterisk eXchange (IAX) is a communications protocol native to the Asterisk private branch exchange (PBX) software, and is supported by a few other softswitches, PBX systems, and softphones. It is used for transporting VoIP telephony session ...

, and encodes and decodes the voice signal using a voice codec such as

G.711 G.711 is a narrowband audio codec originally designed for use in telephony that provides toll-quality audio at 64 kbit/s. G.711 passes audio signals in the range of 300–3400 Hz and samples them at the rate of 8,000 samples per second ...

G.729 G.729 is a royalty-free narrow-band vocoder-based audio data compression algorithm using a frame length of 10 milliseconds. It is officially described as ''Coding of speech at 8 kbit/s using code-excited linear prediction'' speech coding (CS-ACEL ...

, GSM,

iLBC Internet Low Bitrate Codec (iLBC) is a royalty-free narrowband speech audio coding format and an open-source reference implementation (codec), developed by Global IP Solutions (GIPS) formerly Global IP Sound (acquired by Google Inc in 2011). ...

or others. Since the ATA communicates directly with the VoIP server, it does not require a personal computer or any software such as a

softphone A softphone is a software program for making telephone calls over the Internet using a general purpose computer rather than dedicated hardware. The softphone can be installed on a piece of equipment such as a desktop, mobile device, or other comp ...

. It uses approximately 3 to 5 watts of electricity, depending on the model and brand. Often an ATA is connected between an

IP network The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suit ...

(such as a broadband connection) and an existing telephone jack in a residence to provide service in all locations of the residence where telephones are connected. public switched telephone network (PSTN) providers on all the other telephone jacks in the residence.

References

{{DEFAULTSORT:Analog Telephony Adapter VoIP hardware Telephony equipment