Many people choose Boost Mobile for its pay-as-you-go or prepaid service and its lack of contracts. Often, however, customers wish to use an unlocked phone with the Boost Mobile service, instead of the one that came with their plans. It is sometimes possible to use your preferred phone with Boost Mobile service, depending on the network the phone is designed to operate on.
Most wireless carriers use either the GSM (T-Mobile, AT&T) or CDMA (Sprint, Verizon) networks. Phones -- even if they are unlocked -- that were made to work with these networks will not work with Boost Mobile, which uses the much older IDEN network. There is no way to convert a phone from using GSM or CDMA to IDEN.
Nextel is the only other major carrier that uses the IDEN network. The only unlocked phones that will work with Boost Mobile are Boost phones or Nextel phones.
Using an Unlocked Boost Mobile or Nextel Phone
To use an unlocked Boost Mobile or Nextel phone, open the back cover of the unlocked phone. The SIM card slot will generally be under the battery, but may be located elsewhere on the phone. (Check your phone manufacturer's website for details.) Take out the current SIM card, if there is one. Next, open the back cover of your current Boost Mobile phone (if you have one), and take out your current SIM card. Place the working Boost Mobile SIM card into the unlocked phone, then snap the cover back on and turn on the phone. You should then be able to make calls.