Arthur, As Lightninghorse stated, businesses get around this problem by ordering "terminals" which are POTS lines or PBX trunks with the same identity as the main number. I have all of my offices and hotels set up with terminal hunt groups. I got tired of keeping track of hundreds of different numbers. AT&T in Texas is usually more than happy to change them at no charge. When I purchase a new business or hotel I just call them and have them convert the hunt group to a "terminal" hunt group and all of the secondary roll-over line numbers go away and I am left with the main number and X amount of roll-over lines. When a call is placed on any of the lines in the hunt group only the main number is displayed which is all I ever want anyone calling back on. This cuts down on lots of confusion, etc. I don't worry about the extra work it might take to troubleshoot one of these lines because I give AT&T thousands of dollars every month and when I need service or repair they usually get it done quickly. I am surprised more businesses don't request this type of arrangement.