Startup Idea : Know your position in line - counter visability

It is so annoying sometimes, you go to the post office, or any public place, you take a number and wait 10 minutes, 20 minutes sometimes an hour just so you won't miss your position in line. Why do I need to wait? The idea is to assign each line counter with a unique code, say SJXHSK1HS, develop a global line counters app that all you need to do is open it, enter the line counter code and the line counter is displayed on your screen. No go ahead and do whatever you want, you don't need to be afraid you'll miss your turn since you are in sync with the progress.