to because to wish to add capability to your system such as voice mail or networking with other locations. System lacking in desired capabilities Before you buy an entire new system for a certain capability, make sure that there is no other alternative and that you really need this capability. Some older PBXs cannot display the tele- phone number of the person who is calling you from the outside (Caller ID) on your telephone. This is one function that organi- zations may replace the system to obtain. Often a system upgrade, while it may include the purchase of hardware and software, will be less costly than purchasing an entire new system. System problems that cannot be resolved Replacing a system to solve problems without knowing what is causing them never makes sense. The same problems may be there after the system is replaced since they may have been a result of (1) poor system design, which you may have inadvert- ently replicated (2) outside line problems (3) cabling problems or (4) power problems, to name a few. Before replacing a system, it is important that the problems have been identified and it is agreed that they cannot be fixed. This often takes patience, money and skill on the part of who- ever is diagnosing the problem. At worst, it may take a technician, an administrator, an engineer and a consultant. At the end of the process, the outcome may point to one of the other reasons for replacement such as the system being too old to maintain or at maximum capacity. Or if the problem is not with the system, then a considerable expense may have been avoided. Poor experience with the maintenance company It is always advisable to purchase a PBX that can be sup- ported by a number of different companies in your area. This The Telecom Handbook - 63 PURCHASING A PBX way, if service is not satisfactory, you have options. Some orga- nizations are forced to replace the PBX if no such option exists. A PBX Request For Proposal (with sample questions) Whether you are upgrading an existing system or purchasing a new 