Cell phones connected to high-speed 3G networks constitute an increasingly important class of clients on the Internet. From the viewpoint of the servers they connect to, such devices are virtually indistinguishable from conventional endhosts. In this study, we examine the IP addresses seen by Internet servers for cell phone clients and make two observations. First, individual cell phones can expose different IP addresses to servers within time spans of a few minutes, rendering IP-based user identification and blocking inadequate. Second, cell phone IP addresses do not embed geographical information at reasonable fidelity, reducing the effectiveness of commercial geolocation tools used by websites for fraud detection, server selection and content customization. In addition to these two observations, we show that applicationlevel latencies between cell phones and Internet servers can differ greatly depending on the location of the cell phone, but do not vary much at a given locatio...