Would the feature group paging be an answer to this internal group "Sales" of people? You could set all of them, and only them, up in a paging group and wheneverr they did hear a page then they would know it was a Sales Group call?
There is also the option of building a MCG for all the sales people and have the call transferred to the MCG.
I would say that your problem is more of a training issue that needs to be overcome.

Also you can not change the tone that is sent when a page is initiated, options are the tone or no tone.