A significant challenge facing wireless and mobile networking is seamless global network connectivity. As expected, no single network operator and no single technology dominates the wireless access landscape. Instead, heterogeneity and change characterize both operators and access technologies. On the face of it, such a competitive landscape should support rapid innovation and more rapid rollout of global connectivity. Unfortunately, end users today are still unable to seamlessly leverage the broad array of available networks. Thus, while coverage may be nearly ubiquitous, access is not. One reason for this difficulty is that wireless providers cannot quickly and efficiently enter into the equivalent of roaming agreements. In this paper, we present a system architecture to enable seamless composition of wireless network access across a range of technologies. Importantly, we do not require pre-existing agreements on the part of operators or active involvement on the part of end users. Rather, operators advertise network capabilities and price while users have built-in preferences for cost, performance, battery life, etc. to allow end devices to both choose an appropriate network and to ensure that end-to-end billing takes place appropriately. We have completed an initial system prototype and our performance evaluation is promising for potential future low-overhead deployment.