An analog telephony adapter or analog telephone adapter (ATA) is a device used to connect one or more standard analog telephones to a digital telephone system (such as Voice over Internet Protocol, VOIP) or a non-standard telephone system.
An ATA usually takes the form of a small box with a power adapter, one Ethernet port, one or more telephone ports. Users can plug one or more standard analog telephone devices into the ATA and the analog device(s) will operate, usually transparently, on a VoIP network.
Since the ATA communicates directly with the VoIP server, it does not require a personal computer or any software such as a softphone.
Purpose
An ATA connects between a broadband internet connection and an existing a telephone. ATAs are used by many VoIP companies selling a VoIP service, where the device is used to replace traditional telephone companies. When sold in connection with a VoIP service, the ATA
is often locked so it cannot be used with a competing service, and the
user can only partly change its configuration. Some providers do sell
devices that are not locked and can be used with any compatible
provider. This type of service, which is fixed to one location, is
generally offered by broadband Internet providers such as cable
companies and telephone companies as a cheaper flat-rate traditional
phone service.