I've been running a home based business and I invested in this full feature phone to help me stay organized. It's a single line phone with high end features you would normally see on much more expensive commercial units.
It can be used as a desk phone or mounted on a wall outlet, it's got a built-in voicemail (digital answering machine) with two different outgoing messages and four mailboxes to leave messages on, a 32 number speed dial memory, clear and straight forward control buttons, LCD screen with date, time & message info and many other features.
It comes complete with the original power adapter. Also included is an aftermarket 360 degree swivel for the base of the headset to prevent cord tangling. It's an older item but it's in near mint condition and one of the best quality small business landline phones ever made.
Here's a link to the online manual to assist you in setting it up.
https://www.manualslib.com/products/Ge-2-9985-4057926.html
If you don't currently have traditional landline service you could always use this with a VOIP service like MagicJack, Ooma, etc.
I'd prefer cash, but I'd consider a trade for an older, running lawn mower.