I use the app air map and I can submit my flight plan with the app and it notifies the the correct towers for me and I have to do it every day practically because right now the work I'm doing foe a couple of Solar companies has Smack in the middle of to airspaces that meet the 107 requirements for notification and one of the the areas that I'm doing inspections I"m at altitudes plus 1200 feet. You say what, yes some of the buildings are 550-700 high rise of cell towers now add my allowed 400 feet I'm at take off height for the North las Vegas regional airport, then I have Nellis AFB to contend with not including 2 active heliports 1 for TV station and the other for a very active hospital . So I use that app and it posts my flight plan and notification to the correct towers.