One of the general settings on premicells is not to display the calling number to whomever you're calling. The theory is that premicells are for outgoing calls, and excessive call-ins on premicell lines would tie up available lines for anyone trying to call out to a cellphone number.
There are two notable drawbacks.
If you have to leave a message, the client can't just hit some shortcut to call you back. A nuisance, but the next is becoming a real problem.
There are an increasing number of people who will not answer their cellphone if the calling number isn't displayed. We're finding it time and time again. We'll call a cellphone number through the switchboard and the client won't answer. After a number of attempts, we'll use a normal cellphone and bingo - the client takes the call.
So why don't people answer calls when the calling number isn't displayed?