You arrange to meet someone in a
large building or park but can not give a precise area because neither of you are familiar with the location. Once you both arrive you call each other or text each other saying...for example "I am by the merrygoround in the park . Or "I am at the bar on the 3rd
floor of the hotel." You both PHONANGULATE until you meet face to
face. The word is made up of triangulate..as in Triangulating a position and
phone.
You did not know where to meet until one or both get to the location to get the lay of the land