Stop me if you've heard this tune before: Economic uncertainty shackled results this quarter. In particular, banks and the biggest data network operators weren't very good customers this quarter. Don't blame us for soft results.

This time, Juniper Networks (Nasdaq: JNPR) does the singing. Shares fell as much as 10.7% after the company posted its fourth-quarter results.

Objectively speaking, the quarter wasn't terrible. Sales fell 6% year over year to $1.12 billion and non-GAAP earnings sunk 33% to $0.28 per share. Those numbers may not impress anyone, but they did beat the average analyst's projections.

CFO Robyn Denholm took pains to underline just how unusual the quarter was: "The December quarter was an atypical and unexpectedly weak finish to the year, with reduced spending by some of our largest customers," she said. That's an echo of the preannouncement Juniper published a couple of weeks ago. And the pain will continue a little while longer, while Juniper's long-term prospects remain solid.

More specifically, CEO Kevin Johnson expects hardwired long-haul connections to give way to fixed high-speed wireless networks instead, and one of Juniper's freshest products is designed to fill both roles. The idea is to give service providers the equipment they need for a smooth transition.

That trend is supposedly already affecting the capital spending patterns of Juniper's largest customers. That would be Verizon (NYSE: VZ) and AT&T (NYSE: T) -- the only two companies to account for more than 10% of Juniper's sales in recent years.

This shift shouldn't matter much to the networks' customers, because Johnson isn't talking about how data is piped into your home. Rather, he's looking at the backhaul connections that make the larger networks tick. That's where Juniper lives in general.

Juniper investors would be smart to keep tabs on that trend. Ma Bell and Verizon typically report earnings just before Juniper does, so if you can catch these companies talking about fixed wireless backhaul spending, you should expect good news out of Juniper very shortly. DragonWave (Nasdaq: DRWI) is another useful canary in this coal mine, as the company specializes in microwave backhaul and tends to report a couple of weeks ahead of the telecoms.

Add a whole flock of wireless backhaul canaries to your Foolish watchlist in a single click, or pick and choose your favorite birds one by one: