Many people considering VoIP as a communication solution get confused about whether to use an ATA (Analog Telephone Adapter) or a router for deploying VoIP at home or their office. Let us see where to use what.
First, we need to make it clear that an ATA and a router are different in their functions and capabilities.
An ATA does not provide you Internet access. It only gets your voice ready to be transmitted over the Internet, by converting the analog voice signals into digital data signals and subsequently fragmenting this data into packets. The packet contains important information about its destination, along with the voice data. When an ATA receives packets, it does the contrary: it reassembles the packets and converts them back to analog voice signals which are fed to your phone.
A router, on the other hand, primarily connects you to the Internet. A router also does fragmentation and reassembly with packets. Another main function of a router, from which it takes its name, is to route packets to their destinations. Unlike the ATA, a router communicates with other routers on the Internet. For instance, the voice you send over the Internet passes through many routers before they reach destination.
So, if you deploy VoIP at home or in your business without really needing Internet access, a simple ATA would suffice. If however you need Internet connectivity with your VoIP service, then a router is needed. For example, if you have a LAN and want to connect it to the Internet, then use a router.
It is very likely that devices will emerge in the future which will include both the functionality of a router and that of an ATA, and maybe even the functionalities of other devices like gateways and switches. In the meantime, make sure that the hardware you choose is compatible with the service that your service provider is offering.