A VOIP analog telephone adapter (also, analog terminal adapter), or ATA, is a device used to connect one or more standard analog telephones to a Voice over IP based network. ATA usually takes the form of a small box with a power adapter, one Ethernet port, and one or more FXS telephone ports. Users can then plug one or more standard analog telephones into the device and they will operate, usually transparently of the VoIP network.

ATAs are used by many VoIP companies like Vonage selling a telco-alternative VoIP service, where the device is used to replace a user's connection to an existing telephone company. When sold in connection with a VoIP service like Vonage, Net2Phone the ATA is usually locked so it cannot be used with another company, and the user cannot change very much of its configuration.

ATAs generally use the SIP protocol, and are manufactured by many companies including Cisco, Sipura, Grandstream, Motorola and Siemens.

Check out the links provided here for more information about analog telephone adapters.

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