Windows TAPIs Your Phone

Russell Kay

For telecommunications software developers, Windows 95 is a four-letter word spelled TAPI. Microsoft's decision to incorporate the telephony API into its operating system has fundamentally changed the way most telecommunications programs operate. TAPI eases the work of telecomm-software developers, but it also makes them think about what features are important and how to implement them.

TAPI takes over many of the housekeeping chores from telecommunications programs, centralizing and standardizing these in the OS. First of all, TAPI knows about modems, and it knows what they need to know. Previously, every communications program had to have its own set-up and configuration routines to determine which comm port, speed, and IRQ to use. Now, TAPI automatically determines what modem you have and configures Windows to support it. Whether it's an inter nal, external, or PC Card modem doesn't matter. The system configures itself pretty much without user intervention. Now each comm program simply interrogates the TAPI system; the developer doesn't have to write a configuration routine.

Scott Hunter, vice president for engineering at Mustang Software (maker of Qmodem), maintains that one of the most important things TAPI achieves is having the operating system manage the comm ports, with the result that all programs have access to them. In the old days, if you ran a communications program--Procomm Plus or Qmodem, for example--the first thing that software did was open the comm port. At that point, every other program was locked out from that port, regardless of whether it was actually being used. Hunter says this was a n important technical reason (aside from marketing considerations) that Windows comm programs added faxing capability. Since the port was tied up, the user couldn't fax unless he or she either closed the program or used the program's own fax tool. Under Windows 95, several communications programs can now share the same port, with TAPI managing conflicts and scheduling.

TAPI also centralizes what Windows 95 terms dialing properties, allowing the user to set up appropriate dialing parameters and conditions for multiple locations (home, office, a remote site, a hotel room). The user only does this once, at the OS level, instead of having to reconfigure each different comm program or Web browser every time he or she moves locations.

Remember, the T in TAPI stands for telephony, which opens considerable new possibilities. Say a fax comes in; TAPI answers the phone and routes the call to Microsoft Exchange. In the original release of Windows 95, Exchange didn't support this automatic routing. But a ne w modem driver, Unimodem V (downloadable from http://windows.microsoft.com ), adds this ability. Even without Unimodem V, however, some communications programs can enable routing.