IMHO your cell has caller id, voice mail...if you're at dinner, out with friends or on a date let the call go to voicemail, that's what these things are there for.

Thoughtfull use of features like call forwarding save you and your callers time. If you call my land line it forwards to my cell if I'm away, if I can take your call safely and politely I will....if there's a reason it'll be a while till I return your call there will be a message there to that effect.

One of my podmates has the most annoying personalized ring tones: one sounds like a cat, the other like a crying baby. I've told her to set the phone to stun. she still has that on.

I'd never call from the bathroom, I'll call you back after that. But you'd be amazed the number of folks who do their business....while doing their....
"how can I help you today?"
"flush"
"ew, we don't know each other well enough for that"