If you've been waiting to dump your BlackBerry for an iPhone because you don't want to give up the free BlackBerry Messaging service that allows you to bypass carrier text messaging, then the wait is over.

Earlier this week, Apple announced at its Worldwide Developers Conference in San Francisco that its new iMessage feature that will be baked into the latest version of iOS software due later this year, will offer a similar messaging service that Research In Motion's BBM service offers.

In addition to seeing when and if messages have been received, just like BBM, iMessage will also work over the wireless data network and it will allow subscribers to avoid text-messaging fees.

In this week's Ask Maggie, I explain how the new feature will work, and whether the new iOS 5 will also make it easier to message Google Android users in the same way. I also offer my advice on why new smartphone customers shouldn't buy the iPhone 3GS. And I make the case to another reader in San Francisco for why she should buy the iPhone 4 from Verizon Wireless instead of buying it from AT&T.

Ask Maggie is a weekly advice column that answers readers' wireless and broadband questions. If you've got a question, please send me an e-mail at maggie dot reardon at cbsinteractive dot com. And please put "Ask Maggie" in the subject header.

Dear Maggie, As a current BlackBerry user who will be switching to an iPhone, I am very excited that iOS 5 is introducing iMessage. I don't have a texting plan and enjoy using BlackBerry Messenger to cut down monthly costs. I use the Google Talk app to communicate with my friends and family who have Android phones. Will iOS 5 allow Google Talk to function on the iPhone the same way it does on a Blackberry

Thanks, Jason

Dear Jason, The new iMessage feature in iOS 5 from Apple will certainly be a BlackBerry killer. I know lots of people who have stuck with BlackBerry because they like the BlackBerry Messenger, or BBM, feature that allows them to bypass the SMS text-messaging network. And now you'll be able to use the same feature on Apple iOS devices. So whether you're messaging a friend on another iPhone, iPod Touch, or iPad, you can use iMessage to send the quick messages.

The way iMessage works is that instead of routing the text message over the cellular network using SMS, it sends the message over your wireless Internet data connection. It's basically iChat for iOS, but it makes it very simple to use like the SMS function on your phone. This means that you don't have to pay the 10 cents a text message or sign up for a $20 unlimited text-messaging plan.

But just like BBM, which only works when you're messaging another BlackBerry user, iMessage only works when you're talking to someone using another iOS device. If you want to communicate with someone using a Google Android phone, you'll have to use Google Talk, Google's instant-messaging platform. In the latest version of Android, Gingerbread 2.3.4, Google Talk on Android phones also supports voice and video, too.

Google has created a special Google Talk app for BlackBerry users to make the Google Talk experience easier to use on those devices. But there is no equivalent app from Google available for the iPhone. And iOS 5 won't necessarily change that situation. That said, you can still use Google Talk to chat with Google Android users. But instead of downloading an app, you can access the feature through Google's mobile Web site: http://www.google.com/talk.

Dear Maggie, My husband and I are in the market for new smartphones. So, we walked into both Verizon and AT&T today to compare iPhone prices and packages. Apparently, we had visited an AT&T franchise store first, where they aren't allowed to sell us the iPhone, so the rep talked us into buying the HTC Inspire 4G. We paid $90 each after rebate for the phones. We later found out when we visited the AT&T "corporate" store that we could get an iPhone for $49, which is $150 less than the iPhone at Verizon. We also found out that the Verizon iPhone plan is $50 more a month than the AT&T iPhone plan.

The AT&T rep from the corporate store told us we could return our Android phones and exchange them for the iPhone if we wanted. Considering that we're currently using fancy (not) flip phones, I think the iPhone 3GS from AT&T will suit our needs just fine.

So my question is this:

iPhone 3GS vs. HTC Inspire 4G

If iPhone: iPhone 3GS, 4, or are we crazy not to wait for the iPhone 5

Utterly exhausted from the day, nose hairs permanently damaged from cologne-bathing sales people, and totally perplexed over where to go from here...so I'm eternally grateful for any help.

Thanks, Jenny

Dear Jenny, So my first word of advice to you is this: Before you head to any retail store to buy a new phone, do a little legwork from home on the Internet. You can go to each carrier's Web site and price out the phones and the plans you're interested in. If you need help deciding between different models of phones, check out CNET Reviews for some help regarding specific phones.

Before I answer your specific questions, let me clarify the price comparison for iPhones running on AT&T's network versus iPhones on Verizon Wireless' network. I think the reps in the stores may have misled you. The $49 price tag cited in your question is for the iPhone 3GS, which is a phone that is more than two years old. It's only available through AT&T in the U.S.

AT&T and Verizon Wireless are currently selling the iPhone 4, which was released for the first time in the U.S. about a year ago. The price of the iPhone 4 on either AT&T or Verizon Wireless is the same: $199 for the 16GB version with a two-year contract.

So the $150 difference that the AT&T rep quoted you was really the difference between two generations of devices and not necessarily an "apples to apples" comparison between the same phone on different carrier networks.

I looked online to price out the overall service plans. And I didn't see a $50 difference if you are comparing similar plans. In fact, the Verizon plan is only $5 more a month than a similar offering from AT&T. AT&T and Verizon Wireless charge the same price for voice plans and text messaging. Where the two companies differ is on data. Verizon offers an unlimited plan for $30 a month, and AT&T offers two tiers of service. One tier is $25 for 2GB of data per month and the other is $15 a month for 200MB of data per month.

If you think most of your data usage will be on Wi-Fi and you don't expect to use a lot of data each month, then the AT&T option is less expensive. But it's not $50 cheaper per month. It's only $15 less expensive than Verizon's plan. ($30 for Verizon's unlimited data plan versus $15 a month for 200GB of data from AT&T.)

So now that I've clarified the pricing, let's get to your actual questions:

iPhone 3GS vs. HTC Inspire 4G If iPhone: iPhone 3GS, 4, or are we crazy not to wait for the iPhone 5

If you're deciding between the iPhone 3GS and HTC Inspire 4G, I'd say stick with the HTC Inspire 4G. It's much newer hardware than the iPhone 3GS, which came out over two years ago. And at $90 after the rebate, that's a good deal, considering that this is still considered a high-end phone at AT&T.

To be perfectly honest, I wouldn't recommend getting the iPhone 3GS compared to almost any other smartphone on the market. The iPhone 3GS was first released in June 2009. So it's more than two years old. You may think you don't need the latest and greatest phone, but the older the hardware, the less likely Apple will be to support it or allow new features to run on it. Apple's CEO Steve Jobs recently said that the next generation of Apple's software iOS 5 will run on the 3GS. But the new software hasn't been released yet, and some experts believe it will be missing some features.

Also the software may run slower on the older generation of hardware. My colleague from CNET Reviews Kent German said that's what happened to the iPhone 3G when the iOS 4 came out. So even though you think you'd be fine with the older 3GS, the truth is that the advancements in software are really about improving the user experience. And that's good for anyone, even if you're coming from a flip phone!

But if your decision is between the HTC Inspire and the iPhone 4 or waiting for the iPhone 5, I'd recommend the iPhone 4. The HTC Inspire is a fine phone and it's a great value at $90. So if price is the only consideration, then stick with it. But if you think you'll want the iPhone 5 when it comes out, whenever it comes out, then the iPhone 4 will probably have better resale value.

I hope this was helpful. Good luck.

Dear Maggie, I live in San Francisco, and I'm planning on buying an iPhone 4. Is AT&T's or Verizon's service better

Thanks, Cathy

Dear Cathy, I can tell you without much hesitation that I'd go with a Verizon Wireless iPhone in San Francisco rather than one from AT&T. As I mentioned in my answer to the previous question, the service pricing on Verizon versus AT&T is similar. Also, AT&T's service in cities such as San Francisco and New York City has been abysmal. And even though the carrier says it has added new cell sites and capacity, I still hear lots of complaints from iPhone users in San Francisco.

At the All Things D conference recently, AT&T's head of wireless Ralph de la Vega was questioned by tech writer Walt Mossberg about AT&T's bad reputation for poor service. De la Vega tried to defend AT&T by blaming the poor service on the 8,000 percent increase in data traffic over the past four years. And when he was pressed specifically about service issues in San Francisco, he blamed the local government's unwillingness to let AT&T upgrade its antennas on their cell phone towers.

There are people who would argue that if you get a Verizon iPhone you won't be able to surf the Web while you talk. But if you get an AT&T iPhone in San Francisco, there's a good chance you won't be talking because your calls will be dropped and you won't be surfing the Web anyway, because your data downloads will be so slow. So in my opinion it's a moot point.

Of course, I must clarify that this advice is specific to someone living in San Francisco. The most important thing to consider when buying a new cell phone is the service. First and foremost, does it work where you live, work, and socialize Because if you can't get reception, then the phone and all its cool features are worthless to you.