A lot of people thought that mobile phone number portability would allow them to freely move from one carrier to another without having to buy a new mobile phone. This has not proven to be the case for a couple of reasons:

• Incompatible Technologies: Although the number of mobile phone technologies in use in the United States is decreasing, carriers do not intend to standardize on a single system. However, within two carrier groups that operate on the same technologies, customers theoretically should be able to move:
  • GSM
    • T-Mobile (handset unlocking policy)
    • Cingular (handset unlocking policy)
    • AT&T Wireless (handset unlocking policy)
  • CDMA
    • Verizon Wireless
    • Sprint PCS
  • iDEN
    • Nextel

• Handset Unlocking Policies: The biggest hurdle that customers of one of these five carriers face to being able to use their existing phone on another mobile system using the same technology is their current carrier's handset unlocking policy. Most handsets sold in the United States are electronically locked so that they cannot be used on another carriers' system without the lock first being removed.

  This flies in the face of one of the principles of the GSM system. It was designed to allow customers to be able to physically replace the SIM card in each handset in order to change the phone number, billing, and certain user-defined phone settings, like saved phone numbers.
  

Mobile carrier handset unlocking policies vary widely. Some carriers are willing to unlock a customer's phone after a certain period of use on their system. This period may be quite short or it may be as long as the contract commitment made when the phone was purchased. Other carriers are unwilling to provide support for unlocking customers' handsets at all.

In future articles on Operation Gadget, I will discuss the handset unlocking policies of some of the GSM-based carriers, and why customers may want to consider these policies when choosing a wireless carrier.