Telephony API Server - TAPISRV.EXE
Provides Telephony API (TAPI) support for programs that control telephony devices and IP based voice connections on the local computer and, through the LAN, on servers that are also running the service. If you disable this service, you may not be able to connect to the Internet via Cable/DSL or dialup connection. We'd recommend leaving this file in place.
If this service is running and programs set to run on startup failt to do so, this technote from Microsoft may be of help: http://support.microsoft.com/default.aspx?scid=kb;en-us;272239
A description of services that run under svchost in Windows XP can be found at http://support.microsoft.com/default.aspx?scid=kb;en-us;314056.
A description of default services running under Winodws can be found at http://support.microsoft.com/default.aspx?scid=kb;en-us;Q250320.
Service
Microsoft