Working on redistributing signals as a result of dropped calls for a telecoms outfit
why are you focussing on a Voronoi solution. Essentially it will only delineate space according to existing locations with no reference to appropriate new locations. Those on a simplistic level at least, are better attempted using visibility/viewshed analysis
I was thinking Viewshed and visibility were better tools as well, because you can see how the mountain blocks the line of sight path between the tower/mast and the terrain. I guess if you are analyzing dropped calls that you have as a dataset, and you were using Kriging to map areas of higher drop calls versus lower drop calls then you might use a Voronoi to verify that your Kriging is working correctly, along with other tools like the semivariogram. But trying to use a Voronoi for figuring out if something is in signal path is not the best use for the tool. I mean you can identify local outliers using Voronoi Map tool. Where as the Viewshed analyzes in 3D space the paths from your starting point until something blocks its path and creates a raster showing that terrain that is visible.