Stephen B. Wicker and Stephanie Santoso, The Breakdown of a Paradigm – Cellular Regime Change and the Death of the Wiretap
Comment by: Susan Landau
Workshop draft abstract:
The coming change from a centralized cellular network to an end-to-end architecture imperils both law enforcement surveillance and the content/context model embodied in ECPA and CALEA. This paper explores the nature of the new technology, and suggests possible models for future legislation.
Traditional cellular is a wireless add-on to a network, the public switched telephone network (PSTN), whose basic architecture is highly centralized. The endpoints – the handsets – have virtually no control over how calls are processed. This centralized architecture has enabled wiretaps, pen registers, and trap and trace devices, all dependent on the handset passing content and context information to the network for processing. This centralized architecture is in sharp contrast to the “end-to-end” architecture exemplified by the Internet. The network fabric of the Internet contains routers that generally operate only at the network, data link, and physical layer. Higher layer activity, from transport up to the application layer, resides in the endpoints. Barbara van Schewick  and others have shown that this end-to-end approach provides better performance, is more economical, and greatly spurs innovation relative to centralized architectures. There is thus strong pressure for centralized networks to move towards an end-to-end approach.
Voice-over-IP represents an initial movement in this direction. Though still centrally controlled, VoIP telephony promised to free voice and data traffic from having to follow the same network path. CALEA reigned in this process by requiring a single point (usually in the form of a session border controller) that facilitates the creation of a duplicate packet stream that can be routed to law enforcement. Law enforcement is thus able to “maintain technological capabilities commensurate with existing statutory authority” . Universal Mobile Access (UMA) is a more ominous development. UMA allows cellular handsets to offload data and voice to unlicensed WiFi channels when such channels are available. Once again, a central point of focus – in this case, the network controller – preserves data collection capabilities.
The endpoint of the cellular technology trajectory is becoming clear. A combination of unlicensed spectrum and open-source development will result in a commons-based cellular system with an end-to-end architecture. This paper considers what such a cellular network might look like. Incorporating the work of Elinor Ostrom  and the Open Source revolution , this paper explores how network routing and handset location algorithms can be developed in such a manner that wiretaps, pen registers, and trap and trace devices will be completely obsolete. In particular, the paper considers networks that have no concept of dialing, and have no centralized location databases. Having established a general model for a commons-based cellular system, possible solutions for limited, yet effective support for law enforcement data collection will be considered that acknowledge the nature of the new technology. Consideration of appropriate alternatives to the content/context distinction will also be provided.
 Barbara van Schewick, Internet Architecture and Innovation, Cambridge: MIT Press 2010.
 Freeh, Louis Joseph, “Digital Telephony and Law Enforcement Access to Advanced Telecommunications Technologies and Services,” Joint Hearings on H.R. 4922 and S. 2375, 103d Cong. 7, 1994.
 Hess, C. and Ostrom, E. Understanding Knowledge as a Commons: From Theory to Practice, MIT Press: Boston, 2006.
 Glyn Moody, Rebel Code: Linux And The Open Source Revolution, Cambridge MA: Basic Books, 2002.