As enterprise telephone system manufacturers decide that their research and development efforts are going to be exclusively focused on VoIP, TDM systems will go the way of the dinosaur. The effect on users is going to be more traumatic this time, however, because of one major difference: the design and successful installation of VoIP systems requires more homework and effort on the part of users than did the installation preparation for TDM systems.During the late 1970s and early 1980s, a wave of change swept across the enterprise telephone system industry, which was at that time referred to as the private branch exchange industry. The wave was caused by the technology shift from analog systems, which were the most common at the time, to digital TDM systems. These systems, which were smaller, less expensive to manufacture and simpler to maintain, became the focus of most PBX manufacturers.At that time, the sales spin in the industry was about the benefit the digital PBXs would bring to users as the public switched telephone network became digital. It was a nice sell, but the real reason for the wave became painfully obvious: The manufacturers simply threw all their support to the digital systems and quit developing, upgrading and (ultimately) maintaining the analog systems. Once users became aware of this, the move to digital began. For PBX manufacturers, these were the good old days.Well, the good old days are back, courtesy of the newest enterprise system technology, VoIP. Manufacturers can't make these systems fast enough, nor can they wait to educate users regarding the numerous cost and feature benefits of VoIP.But these good days for VoIP manufacturers, distributors and certain consultants do not necessarily extend to end users. Once again, users are going to be "forced" to change technology, not for their good but because this is what the manufacturers are demanding. In spite of the commitments of the TDM legacy manufacturers to continue to support and upgrade their TDM-based systems, the time will come quickly when the decision to support this technology dies.\u00a0Avaya\u00a0already has announced that its top-of-the-line system will come only in the VoIP flavor. Look for more vendors to soon follow suit.This being the case, it is time for users to understand that they should expect an inevitable, if not sudden, shift to VoIP telephone systems. This shift will begin (as is happening now) with vendor-focused advertising and sales efforts aimed at using the protocol for advanced applications, cost reduction and other benefits to users. However, it will end with manufacturers dropping their TDM efforts entirely. As enterprise telephone system manufacturers decide that their research and development efforts are going to be exclusively focused on VoIP, TDM systems will go the way of the dinosaur.The effect on users is going to be more traumatic this time, however, because of one major difference: the design and successful installation of VoIP systems requires more homework and effort on the part of users than did the installation preparation for TDM systems. Design, network quality, contention and security - all these factors become major issues for effective implementation of this technology. Any VoIP system provider indicating differently should be avoided like the plague.The result is users should begin today to learn what they can about this technology, as the question is not if your company will be implementing VoIP, but when.Horrell is an independent telecommunications consultant, speaker and author in Memphis, Tenn. He can be reached at firstname.lastname@example.org or via his Web site, www.edhorrell.com.