Telephone VoIP adapter
A telephone VoIP adapter (TVA), also called digital telephone adapter, is a device that allows digital PBX (Private branch exchange) telephone handsets to be connected to a VoIP network, using, for example, Session Initiation Protocol.
An ATA (analog telephone adapter) allows analog phones to be connected to VoIP networks.
A Centrex TVA VoIP enables centrex phones and analog-based Centrex phones like BT Featureline.
Some telecom manufacturers have produced hybrid exchanges with TVA-like elements that support IP phones and also have units or cards that allow connection of digital phones.
Whether a standalone TVA or a hybrid PBX is deployed, the intention is to preserve investment in an installed base of telephone handsets, and remove the need to install Ethernet network infrastructure.[1][2]