Trevor,
Further to John's post. Even though the initial call from your customer may be to your home number, when the call is diverted to your mobile, you will still be able to see the number of the person calling (as long as you have caller display). Most phones nowadays also allow you to set different ringtones for different caller groups. So when the wife or the Bank Manager calls, you can choose to ignore it by the ringtone alone. (Not that you would of course).
Did you have a good holiday?
Martin S