The Boost Mobile wireless phone network uses CDMA rather than GSM technology. Boost Mobile is a subsidiary of Sprint Corporation and as such uses their wireless CDMA network.
CDMA stands for Code Division Multiple Access and became the preferred network in North America in the mid-1990s on 3G networks. It carries a smaller footprint than GSM (or Global System for Mobiles) technology but GSM became the dominant global wireless technology in the 21st century; therefore, GSM is preferable if the user travels outside North America.
Boost Mobile is a prepaid mobile phone service offered by Sprint. Sprint does offer some headsets with dual CDMA/GSM technology.