Well, if your company/ network is all macs, then you can develop a program that can make calls through a VOIP server, like a Cisco Call Manager. After you develop that, you can use the Apple utility called Automator to make the program you made call a specific phone number/ extension and play a sound.
Example-
User opens Microsoft Word for Mac.
Automator says, "This file has been opened, tell program example to dial x1234
Program you develop Dials x1234
Automator-Dialing
(Phone is picked up)
Automator- Play file "Rush-Force Ten.mp4"
Something like that.