Or, rather, how has it been responding? Because it’s clear the company has been preparing for this moment for some time. Last year, it accelerated upgrade eligibility for iPhone customers, making it easier for them to get the iPhone 4 when Apple released it. And it locked them all into two-year contracts in the process. And then, last week, it drastically reduced the price of the iPhone 3GS, halving it to $49 from $99.

Presumably, AT&T could follow this with additional pricing promotions that could further limit iPhone subscriber defections to Verizon, though at this point one could argue that it’s as well prepared for its loss of iPhone exclusivity as it will ever be.

Why? Two big reasons:

1. According to Piper Jaffray analyst Christopher Larsen, nearly 80 percent of AT&T iPhone users are currently on family or corporate plans, which makes switching to a new carrier a difficult proposition.
2. Approximately 75 percent of them still have at least a year left on their contracts.

And there’s a third wild-card reason as well: How Verizon’s network fares after a big influx of data-heavy iPhone subscribers. That’s tough to predict, but two analysts I’ve spoken with said they expect Verizon to suffer some network growing pains, though not as bad as the ones suffered by AT&T. Ultimately, Verizon is starting off with a better network, and CDMA is said to be a more spectrally efficient standard than UMTS.

So will there be some AT&T subscribers who switch to Verizon when it begins selling the iPhone? Certainly. But they may not be nearly as large in number as you might think.

“AT&T has done everything it can,” Needham and Co. analyst Charlie Wolf told me this morning. “The company locked in a lot of iPhone owners by waiving early termination fees last summer. It’s moved aggressively to add a bunch of BlackBerrys and Android phones. And it should be remembered that AT&T will continue to sell the iPhone. So I doubt that the loss of subscribers to Verizon will be that large. But it could be material as it pertains to the bragging rights between AT&T and Verizon. “

PREVIOUSLY:

• Why Verizon’s iPhone Won’t Be So Bad for RIM
• How Might the Verizon iPhone Differ From the iPhone 4 (Besides Being Able to Make Calls)?
• Tired: Speculating About Verizon iPhone. Wired: Speculating About Verizon iPhone Sales.
• Verizon iPhone to Debut With Unlimited Data Plan
• Apple CEO Likely to Appear at Verizon iPhone Event
• Verizon Event Set for Tuesday–iPhone Time

But only because those who speculated about the existence of a Verizon iPhone have been struck by a new monomania: Speculating about first-year Verizon iPhone sales numbers.

Indeed, the sales estimates are already rolling out, with the consensus so far hovering between nine million and 12 milion.

“Some think 10 million is possible in the calendar year,” Wedge Partners analyst Brian Blair told me. “And I think it’s a reasonable assumption–not just because of what we’ve seen on AT&T but because you have three years of pent-up demand from users who are loyal to the Verizon network because of its coverage and reliability.”

Gleacher & Co. analyst Brian Marshall agrees, though he’s betting on sales hitting the top end of the range I mentioned.

“The iPhone on Verizon will sell 12 million units in calendar 2011 assuming there’s a ramp-up similar to the one AT&T experienced in 2007-2008 (i.e., 5 percent penetration of the postpaid subscriber base within five quarters of launch),” he told me, adding that AT&T will see a material decline in its iPhone sales as a result.

Taking a more conservative view of the iPhone’s prospects on Verizon is Piper Jaffray analyst Gene Munster, who expects Verizon to activate roughly 25 million smartphones in calendar 2011, of which nine million will be iPhones.

Barclays Capital analyst James Ratcliffe too is betting on that nine-million figure, and of those he expects approximately 500,000 to one million to be purchased by AT&T switchers. Said Ratcliffe, “We don’t believe that the addition of a Verizon iPhone will be a seismic event in the wireless competitive environment, although we do expect it to result in a modest spike in AT&T churn, as customers who love their iPhones but have become unhappy with AT&T’s network take advantage of the alternative.”

PREVIOUSLY:

• Verizon iPhone to Debut With Unlimited Data Plan
• Apple CEO Likely to Appear at Verizon iPhone Event
• Verizon Event Set for Tuesday–iPhone Time

Here’s one way: By offering it with a wireless service plan free of the data caps used by AT&T.

Sources close to Verizon tell me the carrier will offer the iPhone with an unlimited data plan (presumably the same $30 unlimited plan it offers for other smartphones)–though they wouldn’t say for how long. That should distinguish it a bit more from the iPhone on AT&T, which requires a capped plan for data service.

Not that such differences worry AT&T any. “We think customers will prefer AT&T’s faster speeds and better functionality over a CDMA network device,” a spokesperson told me. And he has a point. AT&T’s UMTS network allows the use of data and voice simultaneously. Verizon’s CMDA network doesn’t–at least not yet. So, initially, Verizon iPhone users won’t be able to use the Web or check email while on a call–something AT&T iPhone users have long been able to do.

All Things D reported Friday that the special event Verizon is holding in New York Tuesday will be the carrier’s long-rumored iPhone announcement.

PREVIOUSLY:

• Apple CEO Likely to Appear at Verizon iPhone Event
• Verizon Event Set for Tuesday–iPhone Time

It’s going to be T-Mobile.

That’s the theory put forth by Kaufman Bros. analyst Shaw Wu, who argues that the carrier is a more likely candidate than Verizon (VZ) because its network wouldn’t require Apple (AAPL) to build a separate iPhone to support it.

“Currently, T-Mobile’s 3G service (UMTS/HSPA) supports 1700 MHz and 2100 MHz frequencies while AT&T supports 850 MHz and 1900 MHz frequencies,” Wu wrote in a note to clients today. “Interestingly, both the new iPhone 4 and iPhone 3GS support 3G at the 2100 MHz frequency and, from our understanding, the technical hurdle to support T-Mobile is minor compared to supporting CDMA technology at VZ and Sprint.”

That would certainly make the transition to multiple carriers in the U.S. easier for Apple, which would surely prefer not to have to customize the iPhone to gain increased distribution. But the payoff would be significantly reduced.

Today, Verizon is the largest U.S. wireless carrier, with 93 million subscribers. T-Mobile has just 34 million. A deal with the former would nearly double the iPhone’s addressable market; a deal with the latter would increase it by a little more than a third.

Unless Apple brought the iPhone to both T-Mobile and Sprint (S). Says Wu: “It is notable that signing up both T-Mobile and Sprint would almost be the equivalent of signing VZ.”

Of course, as Wu himself notes, Sprint’s network is CDMA and would require a customized iPhone, just like Verizon. So if Apple were to sign a deal with Sprint, it may as well sign one with Verizon.

Today, Google rolled out a new version of the device that supports both quad-band GSM/EDGE and tri-band 850/1900/2100MHz UMTS and will run on AT&T’s 3G network and Rogers’s as well. Sadly, neither is available with a service contract, which means no subsidy.

So if you’re an AT&T (T) or Rogers customer and you’d like a Nexus One, you’ll have to pay the full unsubsidized price for it: $529. That will undoubtedly limit its popularity on both carriers. Still, an increase in distribution is an increase in distribution.

Nexus One now compatible with the AT&T 3G network and shipping to Canada

In early January, we announced the Nexus One, the first device sold through Google’s web store. The Nexus One is unlocked, which means you can use it with a SIM card from most GSM operators worldwide. Currently the device is compatible with most 3G networks, including T-Mobile in the US. However, there are some carriers that have different 3G frequencies, such as AT&T in the US and Rogers Wireless in Canada, so users with these SIM cards can only access 2G or EDGE networks on their Nexus One.

Starting today, an additional version of the Nexus One is available from the Google web store that is compatible with AT&T’s 3G network. This new model can be purchased as an unlocked device without a service plan. In addition to AT&T’s 3G network, this device will also run on Rogers Wireless in Canada. And like the first version of the Nexus One, it can be used with most GSM operators globally.

Additionally, Nexus One devices can now be shipped to Canada from Google’s web store, and will work with a SIM from Rogers Wireless.

As I write this, Palm is trading at $6.10–up an astonishing 85 percent since its big announcement. And it seems destined to go higher still, given the enthusiastic reception analysts have given it.

Deutsche Bank’s Jonathan Goldberg raised his rating on Palm (PALM) to Hold from Sell saying this morning that he is impressed with the Pre and the direction in which the company is now heading.

“Our thesis on Palm has been that its future is a binary outcome,” he wrote in a note to clients. “We are favorably impressed with the new device and more importantly with the new WebOS. We think the focus has now shifted from their mere survival to execution. The earnings model has the potential for significant earnings leverage, but our outlook is tempered by Palm’s history of missteps. We think they can ship 1m units FY09 and 4m in FY10. The stock has run significantly over the past two days reflecting this, but as we learn more about the popularity of the OS and the potential for them to actually ship a UMTS version of the Pre this year we will revisit our thesis.”

Obviously, there are a few noteworthy caveats in there. Still, Goldberg’s note is vastly different from the funereal notes analysts were writing about the company less than a month ago. Indeed, on Dec. 18, Canaccord Adams analyst Peter Misek essentially dismissed the company. “Due to increased competition in the industry, Palm has lost its place as a leading smartphone manufacturer and has gradually become less relevant as more competitors have introduced more innovative smartphone devices,” Misek said. “The company is financially distressed and lacks any viable future catalysts which could help restore profitability…. We believe that Palm has become largely irrelevant in the smartphone space due to a series of strategic errors and poor execution.”

Clearly, Palm’s situation has changed for the better. Now, let’s see for how long.

As I write this, Palm is trading at $6.10–up an astonishing 85 percent since its big announcement. And it seems destined to go higher still, given the enthusiastic reception analysts have given it.

Deutsche Bank’s Jonathan Goldberg raised his rating on Palm (PALM) to Hold from Sell saying this morning that he is impressed with the Pre and the direction in which the company is now heading.

“Our thesis on Palm has been that its future is a binary outcome,” he wrote in a note to clients. “We are favorably impressed with the new device and more importantly with the new WebOS. We think the focus has now shifted from their mere survival to execution. The earnings model has the potential for significant earnings leverage, but our outlook is tempered by Palm’s history of missteps. We think they can ship 1m units FY09 and 4m in FY10. The stock has run significantly over the past two days reflecting this, but as we learn more about the popularity of the OS and the potential for them to actually ship a UMTS version of the Pre this year we will revisit our thesis.”

Obviously, there are a few noteworthy caveats in there. Still, Goldberg’s note is vastly different from the funereal notes analysts were writing about the company less than a month ago. Indeed, on Dec. 18, Canaccord Adams analyst Peter Misek essentially dismissed the company. “Due to increased competition in the industry, Palm has lost its place as a leading smartphone manufacturer and has gradually become less relevant as more competitors have introduced more innovative smartphone devices,” Misek said. “The company is financially distressed and lacks any viable future catalysts which could help restore profitability…. We believe that Palm has become largely irrelevant in the smartphone space due to a series of strategic errors and poor execution.”

Clearly, Palm’s situation has changed for the better. Now, let’s see for how long.

I attended the iPhone launch event, and was able to use one for a little while. That’s too brief an encounter to allow me to write a proper review. But I can say that it has the largest and most beautiful screen I’ve ever seen on a cellphone, even though it’s incredibly thin. It felt great in my hand. It has a brilliant new user interface; the handsomest email program and Web browser I’ve ever seen on a phone; a full-blown iPod music and video player built in; and even a cool new voicemail system.

The iPhone has some potential downsides — it doesn’t use a physical keyboard, instead relying on a virtual keyboard on the screen, which may put off heavy email users. It runs on the relatively slow EDGE cellular data network, though that flaw is partly offset by the fact that it can also use speedy Wi-Fi wireless networking. And, with a $499 base price, it’s expensive.

Still, the iPhone made my relatively new Treo 700p seem primitive in many respects when I compared them side by side. And the Apple product isn’t Palm’s only problem.

Palm’s position as the design leader in smart phones has been under assault for months. Major phone makers like Motorola and Nokia have introduced models that have most of the Treo’s capabilities but are thinner, sleeker and lighter — and much less expensive.

The Treo maker is starting to respond, but haltingly. It has brought out a couple of slightly smaller new models, but they’re no match in sleekness or style for competitors like the Motorola Q. They also aren’t as cheap. They do, though, have some advantages in software and functionality that, for some users, will make them preferable.

I’ve been testing the latest skinny contender, the Samsung BlackJack, along with Palm’s newest Treo, the slimmed-down Treo 750. Both of these phones — like the Apple phone — run on the Cingular Wireless network. Both also use Microsoft‘s Windows Mobile software.

The new Treo 750 is slimmed down a bit from the familiar Treo 700 and 650 models. The 750 is also a little shorter, because it does away with the protruding antenna. In addition, it’s a hair thinner and about 16% lighter.

But next to the new Samsung BlackJack, the Treo 750 looks bulky. The BlackJack is a striking, all-black model in the slim tradition of the Motorola Q. It manages to cram a full keyboard, like the Treo’s, into a body that is much sleeker and better looking. The BlackJack is 35% lighter — and 36% smaller overall — than the Treo 750. It has a physically smaller screen, but that screen has a third better resolution than the Treo’s. (Of course, both screens look tiny and grainy compared with the display on the new Apple phone.)

Also, the BlackJack claims 38% better battery life than the Treo, and it runs on a faster data network than the Treo. (Neither phone includes Wi-Fi.) And, to top it all off, the BlackJack is half the price — $199, compared with $399 for the Treo 750.

One of the Treo’s biggest advantages has been its Palm software, which I consider to be better designed for email and phone calls than the Windows Mobile software from Microsoft. But the new 750 model can’t claim that advantage because, while it has Palm hardware, it uses the Microsoft software.

The Treo does have a small software advantage over the BlackJack. It uses a fuller version of Windows Mobile that has more features than the stripped-down version used on the BlackJack and the Motorola Q. And, because it has a touch screen, the Treo is easier to navigate than the BlackJack, which must be controlled with buttons and a scroll wheel on the side.

Also, the Treo’s control pad felt better to me than the BlackJack’s, which was cramped. I kept hitting other buttons on the BlackJack while trying to scroll or select icons.

In my tests, both the Palm and the Samsung sent and received voice calls well. Both also exhibited the clumsiness that is inherent in Windows Mobile — multiple key presses were needed to do simple tasks. Both have basic cameras with resolutions of 1.3 megapixels. (The Apple iPhone’s camera will be two megapixels.)

The BlackJack runs on Cingular’s new broadband data network, called “3G” or HSDPA, while the Treo 750 uses a slower network called UMTS. Oddly, however, in my tests, the Treo was generally as fast or even faster at retrieving Web pages than the BlackJack.

Of these two phones, I prefer the BlackJack. But if you’re in the market for a smart phone and can afford $499, you might want to wait until June for the Apple iPhone. The Apple entry is so full of promise that anyone buying a smart phone in 2007 should at least wait for the full reviews and a chance to try it out.

Email me at mossberg@wsj.com.