TAPI 2.1 (Telephony Application Programming Interface) is included in Windows NT 4.0 Service Pack 4.
To enable the new TAPI, create a new admin account on your server for the TAPISRV service. Give it a non-blank, non-expiring password.
At a CMD prompt, type:
tcmsetup.exe /s domain\UserName password
where domain, UserName, and password are for the new TAPISRV account.
You should receive an acknowledgement stating that the server was properly set up.
Restart your server.
To enable TAPI on an SP4 client, logon as a domain admin and at a CMD prompt, type:
tcmsetup /c ServerName
where ServerName is the name of the TAPISRV computer.