The company behind a cutting-edge technology used by major wireless carriers is embarking on its final two-month test phase, a crucial step in determining the future of the technology. According to company executives, this testing period holds significant importance. Chris Wade, the CEO of Cambridge Positioning Systems, the company responsible for developing Enhanced Observed Time Difference (EOTD) technology, emphasized the intensive focus and dedication being channeled into this phase.

In the realm of telecommunications, all U.S. carriers are striving to comply with a 1996 federal mandate that requires them to pinpoint the location of cell phones dialing 9-1-1 within 100 yards. While satellite-based systems have demonstrated adaptability to this standard, the land-based EOTD system encounters challenges in rural areas due to a sparse distribution of base stations essential for call location.

EOTD’s methodology involves leveraging up to four cellular base stations to triangulate a cell phone’s position by analyzing the arrival times of signals at different antennas. However, in rural settings where base stations are miles apart, this approach may prove less accurate, with potentially only two base stations available for location determination, as noted by Wade.

Wade underscored the unique complexity of developing EOTD, highlighting the innovative nature of the technology and the substantial time investment it demands. Despite encountering hurdles, EOTD has excelled in urban testing scenarios, exceeding established standards.

The three carriers utilizing EOTD have alerted the Federal Communications Commission (FCC) about anticipated delays in meeting the June deadline, citing challenges in producing EOTD network infrastructure and compatible handsets. Cingular Wireless communicated its readiness to discontinue EOTD in 2003 if operational equipment is not yet available.

Upcoming tests are slated to take place on network equipment provided by Cingular in San Francisco, AT&T Wireless in Dallas and Portland, and VoiceStream in Washington, Rhode Island, and Texas. The technology must achieve a two-thirds accuracy rate in locating 911 calls within 100 yards—a requirement stipulated by the federal E911 accuracy mandate.

Acknowledging the setback in schedule, Wade acknowledged the inherent complexities in achieving flawless technology performance, noting variations in accuracy levels across different geographic regions. The FCC is deliberating on the carriers’ requests for deadline extensions to address EOTD-related issues, typically accommodating such appeals. Notably, AT&T Wireless faces a proposed fine of $2.1 million, while Cingular Wireless has committed to a $100,000 contribution to FCC regulators.


  1. What is the purpose of the final two-month test phase for the technology?

    • The test phase is crucial in determining the future viability of the technology.
  2. What challenges do U.S. carriers face in complying with the 1996 federal mandate?

    • U.S. carriers must ensure that cell phones dialing 9-1-1 can be located within 100 yards, presenting difficulties for land-based systems like EOTD in rural areas.
  3. How does EOTD determine a cell phone’s location?

    • EOTD utilizes multiple cellular base stations to calculate a phone’s position by analyzing signal arrival times at different antennas.
  4. Which carriers are involved in the testing of EOTD network equipment?

    • Cingular, AT&T Wireless, and VoiceStream are conducting tests on their respective network equipment.
  5. What accuracy rate must EOTD achieve for locating 911 calls?

    • EOTD must locate two-thirds of 911 calls within 100 yards, as mandated for E911 accuracy.
  6. How does the FCC respond to carriers’ requests for deadline extensions?

    • The FCC typically grants deadline extensions to address technology implementation challenges.
  7. What repercussions do carriers face for delays in EOTD implementation?

    • AT&T Wireless is facing a proposed fine, while Cingular Wireless has committed to a voluntary contribution to FCC regulators.
  8. Why is EOTD particularly challenging to develop?

    • EOTD represents a novel and intricate technology, demanding significant time and resources for development.
  9. In what geographic areas has EOTD demonstrated success?

    • EOTD has excelled in urban testing scenarios, surpassing established performance benchmarks.
  10. What is the primary concern for carriers regarding EOTD accuracy?

    • Carriers aim to strike a balance between high accuracy levels in some areas and potential accuracy limitations in others.
  11. What role do base stations play in EOTD’s functionality?

    • Base stations are essential for triangulating a cell phone’s location using signal arrival time measurements.
  12. What repercussions do carriers face for delays in EOTD implementation?

    • AT&T Wireless is facing a proposed fine, while Cingular Wireless has committed to a voluntary contribution to FCC regulators.


As the company behind the innovative Enhanced Observed Time Difference (EOTD) technology conducts its final two-month test phase, the future of this cutting-edge technology hangs in the balance. The technology, designed to enhance the location accuracy of 911 calls made from cell phones, faces challenges in rural areas due to the sparse distribution of base stations.

Despite the hurdles, EOTD has shown promise in urban testing scenarios, exceeding performance standards. Carriers are striving to meet federal mandates for E911 accuracy, with the technology’s accuracy levels being scrutinized closely. The FCC is considering requests for deadline extensions to address implementation issues, a process typically accommodated by regulators.

The intricate nature of EOTD development underscores the technology’s complexity and the significant investment of time and resources required for its advancement. While setbacks have been acknowledged, there is optimism about the technology’s potential. Carriers are navigating the challenges posed by EOTD implementation, with regulatory implications looming for compliance issues.

For readers interested in exploring the evolution of EOTD technology and its implications for the telecommunications industry, staying updated on the progress of the final test phase and regulatory developments is essential. The intricate interplay between technological innovation, regulatory compliance, and industry dynamics underscores the importance of closely monitoring EOTD’s journey in the telecommunications landscape. Stay informed and engaged to witness the unfolding impact of EOTD technology and its role in shaping the future of wireless communications.