not everyone gets usable cell reception at home. we had to get a landline when we moved to a new condo where our cells don't work reliably. And to this day I don't have the slightest idea what the phone number is on that landline...
To the OP: cell phones come with built in answering machines and are wireless by nature. And telemarketers aren't allowed to auto dial them. I'd recommend getting one of those. Maybe like the one in your avatar.
Cell Fusion: Mobile/Home Phone Integration
-For Use With Bluetooth Enabled Mobile Phones
-Use Your Mobile Phone Plan From Home Phone
-Answer Your Mobile Calls From Home Phone
-Dial Mobile Calls From Home Phone
-Switch Between Mobile & Home Calls
-Conference Your Mobile & Home Phone Calls
-Displays Caller ID Info
-Displays Call Timer