Now you just have to find a way to enable passersby to connect to the Taza display via their phones.

Your starting assumption is that people will want to do this.

Makes sense, right?  People are clearly obsessed with their phones: heads tilted down, thumbs flicking screens, always.

So isn't it safe to assume that people will want to use these beloved devices to make a Detour Guy move his flag?

At this point, the reader of this may be saying, "No way. Not my phone." 

Now you get that. Then, you didn't. 

You thought that all you had to do was cobble together some connectivity options into a small, easily-accessible control panel.

A tap, or a swipe, or a click -- or even just proximity -- would facilitate a connection between a passing phone and the Taza display. 

Plenty of technology buzz confirmed your assumption; plenty of new technologies were promising to help make that connection: between people, their phones, and what you wanted to connect them to. 

Just to make it interesting, you started with the newest, sexiest connectivity option: an iBeacon.