i would like to be able to network a landline phone to my laptop and send signals through an direct Ethernet cable to it but i need to know what signals the phone accepts and what to send to it to have a voice come through on the phone

If you are willing to compromise on your spec, a softphone will greatly simplify what you are trying to do. You'll need a phone provider gateway, phone.com is probably the cheapest at like $10 a month, a little more if you use their softphone which if you have fiber isn't terrible, if you are on copper just don't be doing anything else.

landline phones don't generally take ethernet cables, so we need to know more here.

you can use an old time modem to do quite a lot with a phone. You can turn off the old handshake noisemaker thing and just tx/rx actual sound data, for example, and to dial it. You can still buy external modems and probably get a USB type cable to it for a modern laptop that has no phone connector. This info may or may not be anything like what you are asking, though. Its just one easy way to plug a phone to a PC. They also make phones that are designed to talk to PC, but I am not sure what cables they use or if its a mixed bag of USB/ethernet/other.

Softphones are awesome. The above is like 1995 hackery.