@Inproceedings {export:117737, abstract = {  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 end-hosts. 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 application-level latencies between cell phones and
Internet servers can differ greatly depending on the location of
the cell phone, but do not vary much a