An improved mobile connectivity system and method allow for data transfers, such as related to service delivery, to and from mobile wireless units in an economical and secure manner. The system utilizes existing IP connectivity when available and otherwise determines an appropriate data exchange mechanism based on the length and security requirements of the intended exchange. Data exchange mechanisms include SMS, IP and other suitable protocols, and wireless carriers include cellular and non-cellular wireless carriers. In an example, each subscriber unit periodically, or when triggered, sends its location to a call center to allow the delivery of location-based services.