Kicking your contract

Q: I have been told by my carrier, T-Mobile, that my Motorola V60g will be incompatible with its new voicemail system, and I'll need to upgrade my phone. Can I purchase a GSM phone without service from another dealer and just switch out the SIM card? This way, I could keep everything the same with T-Mobile and pay the same month-to-month cost without being locked into a new contract--right?
--Chris

A: You probably can make this work, Chris, but you'll need to keep a couple things in mind. In order to buy a phone from a third-party dealer, you'll need to make sure the phone is unlocked. That means the phone is not locked to any carrier; of course, if it's locked to T-Mobile, then you're good to go. That also means you can't buy a phone at a Cingular store and just switch out the SIM card because that handset will not work. Carriers used to be willing to unlock phones for a fee, but lately they've been reluctant to do so. There are hacks available, but I can't guarantee they'll work.

Fortunately, though, unlocked phones are available in many stores and online, and you can always buy a phone from T-Mobile without signing a new contract (don't let the reps tell you that you have to). But there's a caveat. Because you're not buying the phone with a service agreement, you won't get any rebates, and you'll wind up paying full price for the mobile. You'll also need the necessary data settings from T-Mobile.

Back to basics

Q: I live with my phone constantly, and I don't need to take pictures, play games, or download the latest ring tones. Why can't there simply be review criteria that consist of a category entitled "sounds like your landline desk phone." I simply want a mobile phone to have the same quality as my office phone.
--John

A: First off, there are plenty of basic cell phones on the market. We keep a list of CNET's favorites that don't have a camera or any other frills. That said, it would be difficult to rate a phone as "sounds like your landline desk phone" in our reviews. Call quality is ultimately subjective, and it varies sharply--even for the same kind of phone--according to the user's geographic location, the numbers of callers using a carrier at a given time, and the atmospheric interference. Also, because they are wireless, most mobiles just won't sound exactly like your office phone. Unfortunately, it's just their nature.

Technology tussles
Q: What exactly is the difference between CDMA and GSM, and how does that translate to real-world functionality?
--Munim

A: You could write a book describing the technical differences between the two technologies, but I'll spare you the gritty details by describing how these variations may influence your mobile shopping decisions. In the most general sense, CDMA sends wireless signals in a series of unique codes, while GSM divides signals into a series of individual time slots (for more information, see the glossary in our quick guide to 3G). To you, that means a few things. CDMA networks tend to have more capacity so that more callers can use the network at one time, and they tend do a better job during handoffs, when your call is passed from one tower to another. CDMA also has more widespread coverage in the United States, especially when you count analog roaming, and offers more stateside high-speed data networks. Finally--and I know I'm opening a Pandora's box here--CDMA supporters, who are likely to be the most vociferous defenders, usually argue that their technology offers better call clarity. Keep in mind, though, that it's not necessarily a fact since individual call quality is a matter of opinion, and it depends on a multitude of factors that can be beyond your control.

On the other hand, GSM has its own advantages. GSM's advocates argue that because it is a newer technology (though it is based on the older TDMA networks), it's better equipped for the conversion to 3G. This is open to debate though, because for the time being, Verizon has the most extensive 3G network in the States with V Cast. Also, GSM is more widely used than CDMA, with service available in more countries around the globe. CDMA is adding regions as time goes on, but if want a true world phone, GSM is your choice. GSM also uses a SIM card, so it's much easier to switch your phone number and your contacts between handsets. And speaking of phones, GSM phones usually have longer battery life than CDMA mobiles, and at least in the United States, the GSM carriers (Cingular and T-Mobile) have a more varied selection of phones that include such higher-end features as Bluetooth than do CDMA providers Sprint and Verizon.