On the Sprint Nextel earnings call Monday, CEO Dan Hesse said that attractive handset offerings are a hugely important factor in getting ordinary customers to stick with his company. A survey out late last week from IDC gives a clearer picture of what that means for the providers themselves. Hint: Think smartphones, try not to think about the economy, and don’t expect leadership from the bigs.

According to Ryan Reith, a senior research analyst with IDC’s Mobile Phone Tracker, smartphone sales may account for fully half of all handset sales for the biggest mobile providers such as Sprint Nextel. Smartphone sales climbed 4% year-to-year even while overall handset sales dropped a nasty 15.8%.

There’s always a seasonal decline between the Q4 holidays and the austerities of Q1, but the economy -- low demand, tight credit, and currency-exchange misery -- made it all worse; again, that 15.8% reflects year-over-year sales, not a simple sequential slide. Carriers responded in different ways around the globe; in the US, throwing free-phone promotions, cheaper smartphones, and unlimited-usage plans at the problem helped offset the worst of the drop experienced in, say, Western Europe.

And it’s not over yet. Though some regions (China, India) are starting to perk up, Reith foresees at least another quarter of discomfort worldwide, though new features and phones should help brighten the picture.

The top five mobile phone manufacturers, by the way? Nokia may be hurting badly but they’re still #1, with 93.2 million units shipped in the first quarter. Samsung’s next with 45.9 million. Spunky LGE follows with 22.6 million, and that company believes it’s on target for double-digit growth next quarter. Motorola is in fourth with 14.7 million, with that firm showing "signs of improvement to start 2009" according to the report. And Sony Ericsson continues a declining trend with 14.5 million sold.

And speaking of smartphones? "Other" manufacturers -- that category would include Apple, RIM and the Danger/Sharp Sidekick, to name a few standouts -- accounted for 53.9 million units shipped. That’s enough to make the group the second largest handset vendor in the world. If you’re struggling leader Nokia, and especially if you’re any of the phones bringing up the rear of that list, it has to be something of a dinosaurs-vs.-mammals experience to see numbers like these and a trend like that.