Carriers want to optimize their slice of smartphone revenue by controlling their use. Subscribers want to make calls and run applications wherever they are.

Much of this conflict is played out in efforts by hackers to enable phones to work on any network using the same basic transmission standard. This process is called unlocking. A simple but elegant explanation -- and a test to determine whether a particular phone is locked or not -- is available at BlackBerry vs. iPhone.

Gizmodo reports that the iPhone Dev Team is close to unlocking the iPhone 3G. The story says the team broke into the baseband processor of the device, repeating a trick they performed on the first generation iPhone. This, the story says, gives them access to the device's hardware and allows them to free it for use on other networks.

There is more than one way to skin a cat and, apparently, unlock a phone. A chip called SIMable was developed in the U.K. to unlock iPhone and Blackberry devices. The explanation is fascinating in that it is highly physical: A tiny hole is cut in the subscriber information module (SIM) card by a device that the company sells for $29. SIMable then is inserted and the phone is unlocked. The company even claims that the initial manufacturer's guarantee is intact because nothing is done to the handset itself, and that the phone reverts to locked status when SIMable is removed.

Android is not immune to the unlocking phenomena. The first such device -- the T-Mobile G1 -- is, after all, a ripe target. It is new, sexy, and so far constrained to a single network. This piece says that "apparently" T-Mobile will provide users with a SIM unlock code if the subscriber has been with the carrier for 90 days. More information is available at GGIPhone. Another approach, which unlocks to the extent that the device will work on a Wi-Fi network without first activating the phone, is described at Mobile Magazine.

This is, in essence, an executive summary of a much longer academic-style paper to which the author links. It deals with a slightly different type of device locking. The writer says that in August Verizon Wireless will release new firmware for the xv6800, which is also known as the HTC Titan. The firmware locked Qualcomm GPS functionality because Verizon wanted only authorized applications to take advantage of it. This piece says the locking technology is entirely in the phone and is therefore weak. It doesn't say the longer paper provides actual advice on unlocking the functionality, but instead discusses the flaws and shortcomings.

Enterprise IT departments will have policies on how to use iPhone, G1 and other smart phones, including whether they can be unlocked. People at small- and medium-size businesses should carefully consider the consequences of unlocking. Doing so is legal, but generally invalidates warranties.