Uhmm.. Not for anything, but if you're giving out your cell number for
anything other than an emergency contact form, then why are you expecting people to not call you during the day except for an emergency?
If your mobile is your only phone, and you have it set
so loud that you're "hanging up on customers" trying to shut it off, then maybe it's time to re-think things. Maybe you should turn it off at work, or put it in silent mode, select quieter or gentler ring tones... or at least turn the volume down a little. In short, learn how to use your cell phone.
My mobile is my only phone too, has been for over 12 years. I bought my first cell phone in 1995 and never had a land line in my apartments or my house. I've had the same number (minus an area code change) that whole time.
My default ring is a silent one, with a single set of vibrate pulses. Any number not in my phone's address book get's that ring. All my audible ring tones are light instrumental tones that could be mistaken for a passing elevator. If you're in my phone then you're in a group, all of which have a soft ring tone set for "normal" mode and a slightly louder one in "driving" mode. And if the phone is in "meeting" mode
everyone gets the silent pulse/ring. Almost all phones made since 2003 have had these modes (sometimes called "presence" settings), it's just a matter of setting them up.
What annoys me is the "final warning on your warranty" calls I keep getting for everything from my old car to my old appliances. They'd call several times a day, despite me answering on occasion and hitting "2" to take me off the list. And if I waited to talk to an operator the minute I asked who they were with they'd get rude and hang up. I had to put them in a special group and set their voice mail reply to be one that starts with those magical 3 tones indicating the line is disconnected to get the robo-caller to take me off their calling list.