GPS location information might be unavailable if the BlackBerry® device cannot receive signals from GPS satellites. This can occur when something obstructs the signals such as buildings or dense clouds.

To specify the source of GPS location information, you specify the mode by creating an instance of the javax.microedition.location.Criteria class, invoke the appropriate set methods, and pass the instance to LocationProvider.getInstance().

• cell site: Use this mode to obtain location information from cell site towers. This mode permits a BlackBerry device application to retrieve location information faster than the assisted and autonomous modes permit. However, the accuracy of the location information is low-level and does not provide tracking information such as the speed or route. Using this mode requires wireless network coverage and that both the BlackBerry device and the wireless service provider support this mode.
• assisted: Use this mode to get location information from satellites using a PDE. This mode permits a BlackBerry device application to retrieve location information faster than the autonomous mode permits and more accurately than the cell site mode permits. To use this mode requires wireless network coverage and the BlackBerry device and the wireless service provider must support this mode. It is possible that a BlackBerry device user might incur some costs if it uses the assisted mode.
• autonomous: Use this mode to get location information from the GPS receiver on the BlackBerry device without assistance from the wireless network. This mode permits a BlackBerry device application to retrieve location information that is highly accurate and does not require assistance from the wireless network. However, the speed that this mode retrieves location information at is slower than the other modes.

• Retrieve location information from cell site towers
  
• Retrieve location information from GPS satellites using PDE
  
• Retrieve location information from GPS satellites and the GPS receiver on a BlackBerry device
  
• Retrieve location information from the GPS receiver on a BlackBerry device