ewing and editing; password security for mailbox owners and various mes- sage delivery options, such as dialing out to another telephone number or dialing a beeper. Some Service Bureaus offer advanced capabilities such as an Automated Receptionist that will enable your callers to locate you wherever you are, including redirecting the caller to your cell phone. Voice Mail Purchasing Questions When you are purchasing a Voice Mail system, here are some questions to ask: How many ports? This defines the number of users that can be accessing the system simultaneously. How many hours of storage for messages and for announce- ments? What are the maximum number of ports and hours for the system purchased, without having to change the server platform? 110 : The Telecom Handbook CHAPTER 5 Is the operating system Microsoft NT, Windows 2000 or some other proprietary system and what, if anything, does this mean to you? Considerations may be ease of administration (if you know how to administer NT or Windows 2000 for your com- puter network it will be easier to learn to administer a similarly based Voice Mail system) and whether you want to make the Voice Mail system or its administration terminal part of your Local Area Network. Is the Voice Mail capable of Unified Messaging using GUI (graphical user interface) and TUI (telephony user interface)? (See box for definitions of GUI and TUI.) Who will install, service and support the system, and what is their track record with other customers in your neighborhood? (When things go wrong, it helps to have support nearby.) Unified Messaging Unified Messaging has been around for quite a few years and has not yet been widely adopted. Nevertheless, it is being suc- cessfully used in some organizations and others are looking into GUI and TUI (pronounced "goo-ey" and "too-ey") GUI stands for Graphical User Interface. This is a generic name for any computer interface that substitutes graphics for characters. GUIs usually work with a com- puter mouse. The GUI lets users get in and out of pr