 processing power. Many Voice Mail systems are housed on "robust server" type PCs. 2. As with a PBX, the Voice Mail system uses software to provide the intelligence controlling the system features, including the ability to integrate with the PBX. 100 The Telecom Handbook CHAPTER 5 3. The system includes circuit boards called codecs which convert the spoken word into a digital format for storage and then back to an analog voice for retrieval of the mes- sage. The rate of speed at which this conversion takes place is dependent upon the sampling techniques used by the manufacturer to convert the analog signal to a digital form. 4. Hard drives provide the storage for the Voice Mail mes- sages and are also the repository for the announcements and other recordings inherent in the system. PC-based Voice Mail systems or newer telephone systems with Voice Mail included tend to provide more hours of stor- age at a lower cost. Some PBX manufacturer's older Voice Mail systems offer only 10 hours with a 6-port Voice Mail system, while a PC-based system usually provides 80 to 120 hours as standard. Most circuit boards used in Voice Mail systems today are either proprietary or provided by a company called Dialogic. Typical circuit boards may have 4, 12, 16 or 24 ports. The voice mailbox itself is an electronic location in the sys- tem on which messages are held for each system user. The mailbox owner calls in and retrieves messages using a password entered from a touch-tone telephone. He can listen to messages, save them, erase them or forward them to another person's mailbox, with his own message attached. Voice Mail systems offer a variety of functions both for call- ers leaving messages and for mailbox owners. They all perform the basic operations of recording messages, receiving messages and redirecting messages. Additional capabilities vary from one system manufacturer to another. Most Automated Attendants in Voice Mail systems use menus which are treed, meaning that you select a feature from an open- ing menu and are then