There are two competitors in the cellphone industry network worldwide, GSM and CDMA. CDMA (Code Division Multiple Access) works in US through Verizon Wireless. GSM (Global System for Mobile Communication) is a bit older than its rival and it has developed GPRS (Global Packet Radio Service) technology. GPRS has increasingly gained more popularity due to its affiliation to GSM. The majority of network service providers in US use this technology. In fact, approximately 80% from he global cellphone market connect through GSM network as it is the most common standard.As a result of GSM’ popularity, a whole industry trade organization has been created, the GSM Association, including the worldwide mobile phone carriers and manufacturers. The GSM Association estimates that over 4.3 billion people from over 212 countries are GSM users. This technology developed the 2G mobile phone system (2nd generation), making possible the storage into the system more data communication applications. GSM also developed a new way of fast communication worldwide via the short message service system (SMS). The GPRS technology soon developed into EDGE (Enhanced Data Rates for GSM Evolution), a faster way for data transmission. The biggest advantages of the GSM technology are represented by network’s maturity, GSM being more stable, its users benefit from less signal deterioration inside buildings, this type of network is used in all parts of the world making roaming much more accessible.The main difference between the GSM and CDMA technology is the fact that GMS does not allocate the entire frequency to the end-user, being divided in time-slots for a better utilization of the bandwidth. CDMA technology uses the digital modulation called spread spectrum and the entire frequency is available to the user, creating a unique code for each users, allocating bandwidth. This works by spreading the voice data over the channel. When reaching the end-user, the information is added together just like from a puzzle and decoded.Most BlackBerry phones are empowered with CDMA technology, making data transmission faster, although many of them work with EDGE. The issue is that these two technologies are not quite compatible, as they are very strong competitors. So, if your phone works with CDMA, and you travel outside USA, you may encounter network problems. If your BlackBerry works with GSM, it should be OK, as most countries besides USA adopted the GSM technology. In such cases, the best thing you should do is talk to your network provider.