The fourth-generation Apple (Nasdaq: AAPL) iPhone has been introduced, and it's still joined at the hip to AT&T (NYSE: T) here in the States. An imagined hookup with Verizon (NYSE: VZ) Wireless never materialized, and now industry analysts are starting to look for other ways to expand the product's domestic reach.

A research note from Kaufman Bros. Analyst Shawn Wu says that T-Mobile looks like a more likely partner than Verizon -- mostly for technical reasons. Deutsche Telekom's (NYSE: DT) mobile arm relies on wireless communications standards that are very similar to what AT&T uses, while Verizon and Sprint-Nextel (NYSE: S) currently use a very different set of technologies. Therefore, Wu thinks it's more likely that Apple will dangle an iPhone contract in front of T-Mobile before redesigning its hardware and going for Verizon.

So far, I agree. If Apple wants to keep growing iPhone sales at the current clip, it's simply not good enough to stay with a single service provider per market. That's the way Google (Nasdaq: GOOG) is pushing its Android platform, for example, and Apple could perhaps put a crimp in Android's success by going multi-vendor itself.

"Looking at industry data, Android's wins have been where iPhone isn't available and that could change dramatically if the iPhone were available on more carriers," Wu says. Many geographies already have a choice of providers for their iPhones, with predictably positive sales results following. And that compatibility issue does make a difference, so T-Mobile could very well be next in line.

But then Wu spins off into left field when he notes that Sprint plus T-Mobile nearly equals Verizon's American reach, as if Sprint would be next in line after the Germans. Then you're back to redesigning the iPhone again, because Verizon's technical issues with the iPhone are also T-Mobile's. And if you're looking beyond 3G to the next-generation 4G standards, Sprint actually stands alone with WiMax support currently provided by ClearWire (Nasdaq: CLWR), while the other three majors all are going with the LTE standard. You'd see Verizon plus T-Mobile before you could expect a Sprint and T-Mobile coalition over 4G phones of any kind.

Wu's dreamed-up pairing of T-Mobile and Sprint makes me question how credible his sources are, and how clear his thinking is elsewhere. T-Mobile would certainly make a fine iPhone partner when AT&T's exclusive contract runs out, but take the rest with a nice, big salt lick. The comments below are thirsting for your insights and opinions on the iPhone's non-AT&T future.

Fool contributor Anders Bylund owns shares in Google, but he holds no other position in any of the companies discussed here. Sprint Nextel is a Motley Fool Inside Value pick. Google is a Motley Fool Rule Breakers recommendation. Apple is a Motley Fool Stock Advisor pick. Try any of our Foolish newsletters today, free for 30 days. You can check out Anders' holdings and a concise bio if you like, and The Motley Fool is investors writing for investors.