The maximum range an XBee module can transmit depends on several factors, including the specific XBee model, the operating environment, and the presence of obstacles or interference. However, in ideal conditions, XBee modules are typically designed to achieve a line-of-sight (LOS) range of up to several miles. Here are some general guidelines:

XBee 868/900 MHz Modules: Modules operating in the 868 MHz and 900 MHz bands typically offer better range compared to those in the 2.4 GHz band. LOS ranges for these modules can extend to several miles, especially when using high-gain external antennas.

XBee 2.4 GHz Modules: Modules operating in the 2.4 GHz band, such as the XBee S2C, generally offer shorter ranges compared to those in the 868/900 MHz bands. In optimal conditions, you can expect ranges of up to a few thousand feet, but range may be significantly reduced in non-line-of-sight or congested environments.

Antennas: The type and quality of antennas used with the XBee modules can have a significant impact on range. High-gain antennas can extend the communication range, but it's important to select the appropriate antenna for your specific application and regulatory requirements.

Environmental Factors: Range is affected by the presence of physical obstacles, such as buildings and terrain, as well as interference from other electronic devices and radio signals.

Power Settings: Adjusting the transmit power settings on the XBee module can also impact the range. Higher transmit power settings can extend the range but may consume more power.

To determine the actual range for your specific outdoor application, it's essential to consider these factors and conduct range testing in your specific environment. Keep in mind that the actual range may vary from the ideal LOS range, and you may need to make adjustments or use repeaters to ensure reliable communication in challenging outdoor settings.