[Editor’s Note: Below, MobileBeat advisory board member Jason Devitt explains why we should care about new innovative address books. Not only are they key to a much better user experience, but they may greatly impact the way we pay to use our phones. He also looks at how different parties, from carriers to mobile startups, are approaching new address book services from opposing angles.]

There’s a battle brewing for control of your mobile phone’s address book. Make no mistake, Tap Tap Revolution or Twitterberry may get the love, but the address book is the most valuable application on your phone.

There are several reasons why the address book deserves more attention. First off, it contains vital information that is difficult to regenerate. Phone numbers are not like email addresses. They don’t come with signatures attached. And as Xobni has shown, you can rebuild your email contacts on the fly in Outlook simply by mining your inbox. Phone numbers, on the other hand, are almost random, and area codes are increasingly losing their meaning with the rise of virtual phone numbers and number portability. So, if you lose your numbers — unless you have a gift for memorizing 10-digit numbers — you’re out of luck.

Secondly, address books pose a conundrum when it comes to switching carriers. In the U.S., most phones do not have swappable SIM cards. And until recently, few carriers allowed third-party apps to access address books stored in the cloud. Some offer wireless backup and restore functions, but only between their own phones. And some even block you from sharing contacts via Bluetooth. In these situations, you have to hack your phone with a program called BitPim or buy a $40 gizmo like a Backup-Pal or CellStik to transfer your contact information.

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But there’s much more at stake than churn. Service fees are also at issue.

Unlike email, every call and text costs you money, and the amount you pay often varies based on the number you dial. Calls to select numbers are free with some services, out-of-network calls cost more than in-network, international more than domestic and so on. (European readers who are feeling smug about their relatively open phones can stop now — their price plans are far more complicated, causing most calls to cost twice as much.)

Essentially, who you select to call from your address book affects how much money your carrier makes from the call. When you think about it that way, there are a lot of opportunities to improve the system. For example, your address book could tell you that a contact you want to call is currently logged into Skype, allowing you to place a cheap or free call. It could tell you that a friend you plan to text is logged into an instant messaging program, also saving you money. It could even allow you to route your international calls through cost-effective voice-over-internet services like Jajah or Rebtel. If you don’t have the name of the person you want to call in your address book already, it could automatically search for the information on the web and add it.

But not all address books are designed to save you money. Some route your IMs via SMS, attach promotions for particular photo-sharing sites when you send messages containing images, or charge a buck to your account for directory lookups (the same price as 411 today). It all depends on which address book you choose.

Until recently, this choice was hypothetical. Consumers bought phones from carriers, which wielded complete control over all the software on their handsets, including address books. That’s still true today up to a point. It explains why there are no VoIP-over-3G apps on the iPhone. But the rapid rise of smartphones has changed the rules. Carriers make money selling data plans, not selling their own apps. Offering more apps means selling more data plans, and giving up some control leads to a much greater number of apps. Carriers assume that most consumers won’t take the time and trouble to replace their default address books with third-party options.

Enter Facebook. The social-networking site knows who your friends are, knows many of their phone numbers, and already provides you with multiple channels to communicate with them. The first version of Facebook for the iPhone looked much more like a phone address book than Facebook.com for a reason.

Another game changer is Google Voice. It replaces your old cell phone number, and third-party apps like GVMobile and VoiceCentral effectively replace your address book and dialer on your phone with a mobile interface connected to Google Voice and Google Contacts. Google Voice is still in a closed beta, but will make a splash when goes public.

With services like these and others, anything is now possible. Even Twitter was designed with mobile in mind. My Twitter URL is public and easier to remember than my phone number, but you can’t send me a direct message unless I have already chosen to follow you. That sounds like a good model for phone calls too. Why not build an address book that draws from Twitter?

On the other side of the battle, there are companies — and handset manufacturers and telecom vendors too — who think that a souped up address book that takes information from multiple social network sites will allow carriers to get in on the success of sites like Facebook and Twitter without losing control over pricing. Mobile-social connectivity platforms provided by companies like Yahoo, iSkoot and Intercasting (just acquired by Good Technology last week), follow this model.

For these reasons, INQ baked a version of Facebook into its first phone. Several major carriers are also developing Plaxo-style “networked” address books that allow customers to share their contacts with other subscribers only. Asurion, a company that competes with FusionOne to power backup services for carriers, has built a next-generation address book that pulls in status updates and information about all of your contacts from sites on the web. And Zyb has been working on something similar since Vodafone acquired it last year.

Even Palm has built its own version for its highly-anticipated Pre, dynamically merging data from multiple sources into a unified address book. We’ll get to see it when the Pre debuts next week.

Among those who appear neutral — yet to pick a side — are big networks like Plaxo and LinkedIn, directory services like WhitePages.com and startups like DialPlus — and of course, my own company, Skydeck.

This is not a battle between good and evil. Consumers hate complex pricing plans, but if you choose the right one, you’ll end up paying much less than you would in a world of flat-rate pricing. There are companies on both sides of the issue that have an unhealthy obsession with “controlling the customer.”

Proprietary standards, subsidies and tiered pricing (at least for data) will be with us for a long time. But in the next year, we’ll see a lot of innovation around the core communication apps on our phones. And the address book is sure to be ground zero.

Jason Devitt is the chief executive officer of Skydeck, a startup that brings phone services like text messaging, online calls and voicemails to the web. Previously, he co-founded Vindigo, one of the first companies in the U.S. to develop mobile location-based applications for consumers, including MapQuest for mobile phones.

The increasing openness of mobile operating systems and how it relates to next generation address books will be a major topic at this year’s MobileBeat conference on July 16. In particular, a panel discussion titled “Carriers: What do they do now? How do they handle data load but make money too?” will take a closer look at the opportunities and pitfalls involved in this new business. Sign up by June 9 (we’ve extended the earlybird), and save $145.

Image courtesy of Zyb