Thanks for your help.
I should've mentioned that I have my computer getting internet through wifi.
Since the phone needs power, what if I got something like a wall plug PoE injector like this (https://tinyurl.com/29z58rn8)? Would this work if I connected it to both my computer and a telephony service like MagicJack (https://www.magicjack.com)? I can't tell if this would even be possible.
That makes no sense unless the phone itself has wifi - which is unlikely if it's a PoE-powered, ethernet-connected device. It will expect a wired network connection - that is, it needs a wired connection to your router's LAN port.
You won't be able to plug it into your desktop PC unless it has some sort of "connection sharing" feature which allows it to provide connectivity on its ethernet port to other downstream devices. MacOS can do this, but I don't know about Windows.
Is this the one?
https://businessphones.vtech.com/pd/3683/VSP861-Eris...
This doesn't say anything about wifi. (Although it looks like it can act as a DECT base station to connect additional handsets wirelessly, that's not the same thing)
Also, it does say that there's an optional power supply, so it doesn't *have* to be powered over PoE. In that case, plugging a DC power supply in is likely to be better than a power injector.
But like I say: if you can't provide a wired ethernet port for it to plug into, then it isn't actually going to do anything useful. You could buy a "wireless bridge" for it to plug into, but it would likely be cheaper to buy a new VOIP phone with built-in wifi.
BTW, in the UK at least, Vtech is best known for its baby toys
https://www.amazon.co.uk/Vtech-Peek-Play-Phone-Toy/d...