In the interest of full disclosure, I do not yet have an Extend Home analog telephone adapter (ATA) in my possession. I write this from the perspective of one who’s used similar devices (ATAs and IP Phones) with other Voice over Internet Protocol (VoIP) services.
There are two connections that must be made for an ATA to supply telephone service. That is to say, the ATA must be connected to both the Internet (via one’s network) and an analog telephone handset (cordless or corded). Generally, ATAs ship with the needed cables to do so. Those cables are an Ethernet cable for connecting the ATA to one’s network and a standard telephone cable for connecting the ATA to an analog telephone handset. Connecting the latter is reasonably obvious, however, there are options for the former.
Direct Connection to Main Router
Using the included Ethernet cable connect the ATA to an open Ethernet port on the main router. This is the best way to connect an ATA to one’s network. It’s a bit strange for me to be writing this here, however, the best connection for VoIP is via an Ethernet cable to the main router. I say strange to be writing this because Republic’s blended WiFi/cell service on a mobile phone leverages VoIP over a WiFi connection for WiFi calling and text messaging. As we know from experience VoIP over WiFi works quite well, however, a wired connection is even better.
Use Your Wall Phone Jacks
If the location of your main router is not a convenient spot to locate a corded telephone handset or cordless telephone base station, one might leverage their wall phone jacks. A word of caution; for this to work there must not be active POTS (Plain Old Telephone Service) landline service on those wall jacks. If there is, at best, the ATA won’t work. At worst, one might cause permanent damage to the ATA resulting from the low-voltage electrical current supplied on traditional POTS landline service. Please know the fact you aren’t paying for POTS landline service and/or lack of dial tone on your wall jacks does not necessarily mean there isn’t active POTS landline service on those wall jacks. To be certain, one needs to disconnect the telephone company’s POTS wiring at the demarc (the point where the telephone company’s wiring meets your internal telephone wiring. If all this sounds like gibberish, I suggest not attempting this on your own.
Presuming no active POTS landline service, one would connect the ATA to their main router via an Ethernet cable and also connect the ATA to a wall telephone jack near the main router via a standard telephone cable. One may then plug corded or cordless telephone handsets into other available wall telephone jacks more conveniently located.
WiFi Extender or Other Secondary Access Point
If you have secondary access points connected to your main router (wired or wireless), one may connect the ATA to the network via those secondary access points’ Ethernet port. For example, many mesh WiFi systems like Google WiFi have an Ethernet port (sometimes more than one) on the satellites as well as the main device connected to one’s router.
If one lacks a secondary access point, one might consider adding a WiFi extender or travel router. You’ll need to be certain any WiFi extender or travel router purchased has available Ethernet ports to plug the ATA into.
In a nutshell Powerline is a means of running Ethernet over the electrical wiring in one’s walls. Powerline adapters typically come in pairs. One would locate one adapter near their main router connecting via an Ethernet cable. One would then locate the second adapter near the ATA connecting via another Ethernet cable.