Getting the phone number to work?

I am new to this effort but I am working to create a POI of mill and staff locations for my company. using Excel, I use the Presidential Library file as a seed to attempt to get the formatting correct how ever it hasn’t worked very well. Finally I managed to bend the format to work in my GPS and am busy updating it now. here is the question my GPS has the ability to use bluetooth to act as a sort of speaker phone with my cell phone. but I can't figure out how to get the phone number to be recognized as such it simply displays a text is there a format for this use?