A wireless communication facility and method employs a mobile unit having a number of alternative modes of digital wireless communication. The unit may be a battery pack or other accessory device attachable to a wireless telephone handset. The mobile unit is operated to assess some characteristic of each of the alternative modes, and based on the assessment, a preferred mode is determined. Data is transmitted via the preferred mode. The unit may include a GPS locator, so that the transmitted data may include the location of the unit. A call center is connected via the modes, and receives the data for processing, such as to return information to the user about the location.