me for testing before the new software can be released. Once released, these software upgrades can be costly to install and may still have "bugs" to be worked out with fixes called patches. If a customer wants just one of the new features in the new software, he must still pay for the entire upgrade. As switches incorporate more features and thus more software code as demanded by the customers, the chance of system failures and the time required for testing are both in- creasing exponentially. While the manufacturers are being conservative in not offer- ing too many new features too quickly, the switch users have the experience of the programmability of PCs and want the same capability for their telephone systems. The communications equipment "factory" of the future may make each system to the specific requirements of the customer who ordered it. The factory will assemble the network interface modules, the hardware modules and the software modules or pieces into a customized telecommunications solution. The manufacturer's skill where value is added will be in three areas: 1. The Network Interface - The communications server manufacturer will make it possible to connect to T-1/PRI, 156 The Telecom Handbook CHAPTER Z E1 (European equivalent of T-1), SS7, etc. This is not trivial. There are dozens of interfaces to telecommunica- tions networks. There are standards, but the tendency has been towards non-standard interfaces. For example, there are at least 20 varieties of ISDN Basic Rate Interface lines in North America, and even more internationally. 2. Making the communications server rugged, durable, re- dundant, and able to support areas that could be weak such as network interfaces and supplies. 3. Testing of products manufactured by others to work with the communications server. The communications server manufacturer will recommend the software modules, ob- jects and peripheral hardware that will work best with their system. It remains to be seen whether or not they will guarantee the performance of the products