If you are planning to buy a computer telephony (CT) server, here are some features to consider:

* Server OS: Windows NT is best for LAN, database, and messaging connectivity. Vendors also use Novell NetWare, OS/2, UNIX, Windows 95, and MS-DOS.

* Trunk-line support: What types of incoming lines does the server support? All servers handle analog lines. Some servers support DID lines (which let you route calls directly to an extension), Integrated Services Digital Network (ISDN) Basic Rate Interface (BRI) lines (which provide back-end support for BRI phones), and T-1 and ISDN Primary Rate Interface (PRI) lines (which provide the most cost-effective support in 24-line increments).

* Station phone support: All servers handle standard touch-tone phone sets. Some servers support ISDN-BRI phones. A few vendors sell proprietary phones.

* Trunk and station-port capacity per CT server: How many incoming phone lines can a single CT server box accept? How many station phones does a single box support? What are the extra hardware and software costs if you want to expand?

* CT server capacity per LAN: How many CT servers can you add to a single LAN or WAN? Can you administer them as one logical unit or as separate systems?

* Voicemail or auto-attendant option: Is voicemail or auto-attendant a standard feature or an add-on? How many mailboxes are supported? Is message notification support adequate for your needs? Can users easily change their mailbox profiles from their desktop computers?

* Unified-messaging support: Can the mailboxes integrate with standard messaging platforms such as Microsoft Exchange and Outlook? If you are not using Exchange or another email server, is a GUI provided?

* ACD option: Is Automatic Call Distributor (ACD) a standard feature or an add-on? What ability is available to create multiple call queues? Can you define a skills profile for employees and route calls based on that profile? Can you route calls to employees who are off site?

* Screen-pop support: Can you read caller-ID or automatic-number-identification information? Can incoming calls initiate a Screen pop at the destination station via dynamic data exchange (DDE) or Object Linking and Embedding (OLE) integration? Can the system integrate with Open Database Connectivity (ODBC) databases?

* IVR or scripting option: Is interactive voice response (IVR) a standard feature or an add-on? Can you use Visual Basic or some other script language to create an IVR application?

* Call-control support: Can you perform call-control functions from a desktop computer? Is it compliant with the Telephone API (TAPI) or Telephony Services API (TSAPI) standard?

In the past, PBX-enabled CT server solutions claimed to be less expensive than buying separate PBX and voicemail systems. Unfortunately, this statement is not true today. Although CT servers are more expensive, they can do significantly more than a separate PBX and voicemail system solution.

CT servers, however, cost less than separate PBX, voicemail, and ACD systems. Thus, if you need more than just a voicemail and phone system, CT servers can be a great value. Enabling a workgroup with intelligent ACD capabilities in addition to the standard phone and voicemail services is the sweet spot for this product arena.

One caveat applies when you're shopping for a CT server: Some vendors are pricing their solutions with seemingly little regard to the prices their competitors are charging. In some cases, prices can be double those of similar systems from other vendors, so be wary and shop around. Make sure you know ahead of time what features are important to you and compare pricing on the basis of your needs.