Different countries use different frequencies for world-wide deployment. Digi's XBee RF family offers modules, gateways and modems in 2.4 GHz, 902 to 928 MHz, or 865 to 868 MHz bands. The 900 MHz waves penetrate objects and travel better than their 2.4 GHz counterparts. If the designer is in the US, Canada, or Australia they will be better off range-wise using the 900 MHz radios. The 2.4 GHz radios must be used in European countries and where the ETSI standard is required. It is important to be aware of what frequency is required, dependent on where the design application will be deployed.