At one of the companies I used to work for we had a VOIP system, which included a software client for the PC.
This client was used by all the users, and had the possibility to create custom buttons in the main view. These buttons could have all kinds of functionality assigned to them.
What I did was creating a panic button, that when pressed created a small file in a shared folder, containing the name, location and phone number of the user.
I had HM check this folder every 5 seconds, and on appearance of a new file it would then send a type 0 (Flash) SMS to the security guys containing the name, location and phone number of the user that pressed the button.
And then move the file to a "saved" folder.
I'm sure there are more sophisticated ways of achieving this, but this was created with stuff we already had. So no investments or new complicated stuff involved.
Maybe someone can use this someday
