A disclosed location engine estimates a wireless terminal as being indoors or outdoors by utilizing information that includes metadata from previous packet-level transmissions involving both i) wireless terminals that are known to have been indoors and ii) wireless terminals that are known to have been outdoors, while the metadata was collected. Based on this metadata for previous transmissions, one or more classification features are computed. Then, for a wireless terminal that is to be classified during a communication transaction (e.g., voice, data, SMS, etc.) with respect to the terminal being either indoors or outdoors, features that are representative of that wireless terminal for the transmissions are evaluated against a characterization that is a composite of one or more previously-computed classification features. The features that are representative of the wireless terminal can be derived from the metadata associated with the wireless terminal during the transaction being analyzed.