. Historically, separate ports had to be designated for Voice Mail VS. Automated Attendant. When this changed the ports were The Telecom Handbook 97 VOICE MAIL & AUTOMATED ATTENDANT called dynamic ports since they handled both functions. Today's more flexible systems use available ports for either Automated Attendant or Voice Mail functions, depending upon the require- ments of the moment. Some systems are set up as Voice Mail only, even though they have the Automated Attendant capability. A PBX may en- able callers to directly dial each individual extension (called DID or direct inward dialing). If an extension is busy or not answered, the caller hears the Voice Mail greeting of the person he called. As mentioned earlier, most large organizations use direct inward dialing and may reserve the Automated Attendant for callers to a main telephone number or for evening hours when the live switch- board attendant is not there. Voice Mail systems can be connected to outside lines without a PBX, but most work with one. Some of the major PBX manu- facturers, such as Avaya, Siemens and Northern Telecom, sell Voice Mail systems to work with their particular PBXs (their marketing names are Audix/Intuity, Phonemail and Call Pilot/ Meridian Mail respectively). Although these can work with other PBXs, they are designed to integrate with the manufacturer's PBX and often have the appearance of being part of the PBX. There are other major players in the Voice Mail market including Captaris (formerly AVT), Active Voice and some smaller companies. The Voice Mail systems from these companies are often de- signed in cooperation with PBX manufacturers and may integrate with the PBXs as smoothly as the Voice Mail systems sold by the PBX manufacturers themselves. Most of the PC-based systems now have Windows NT operat- ing systems and may have more capabilities at a lower cost, as well as lower upgrade costs than the non-PC-based systems. Some of the newer telephone systems, such as NBX by 3Com, deliver Automated Attendant and Voice Mai