Timing Advance: The Most Overlooked—and Rapidly Expiring—Piece of Cell Phone Evidence Attorneys Need to Understand

By Kevin R. Horan, J.D., Retired FBI Supervisory Special Agent & Co-Founder, Precision Cellular Analysis

In modern litigation, cell phone evidence is everywhere—criminal cases, civil disputes, accident investigations, workplace claims, fraud matters, and insurance litigation. But while most attorneys understand call detail records and tower/sector information, very few realize that one of the most powerful location indicators in cellular forensics is something carriers normally don’t hand over unless you specifically request it.

Timing Advance (TA).

And even fewer attorneys know that TA data can expire in as little as seven days, meaning cases often lose critical evidence before anyone realizes it existed.

This article explains what TA is, why it matters, how fast it disappears, and why attorneys should be requesting it in every case involving cell phone analysis.

What Is Timing Advance?

Timing Advance is a measurement used in cellular networks to estimate how far a phone is from the specific sector of a cell tower. Carriers use it for network timing and synchronization (not for forensic purposes) but the measurement creates a valuable side effect for investigators: an approximate distance from the sector at the time the phone was communicating.

It’s not a “ring” around the whole tower.It’s an arc extending outward from the particular sector that served the device—giving analysts a far narrower and more meaningful location range than tower/sector information alone.

How Timing Advance Is Recorded

TA is often misunderstood as something that is “always running,” but the truth is more precise:

• TA is calculated when the phone reaches out to the network (random access).

• It is updated only while the phone is actively transmitting—calls, texts, data, app activity, or background traffic.

• When the phone is idle, TA does not continuously refresh.

This means TA exists whenever the phone is communicating, often many times throughout the day, even if the user never made a traditional call.

Real-World Precision

TA does not give an exact GPS location. But it is highly useful because:

• It places the phone within a known distance band from the sector.

• In real-world testing, TA usually narrows the phone’s location to within a few hundred meters.

• Combined with sector direction, mapping, and terrain, TA often eliminates large portions of the coverage area.

For litigators, that gap—hundreds of meters vs. miles—can be the difference between confirming or undermining a narrative.

The Data Expires—Fast

This is where most attorneys lose their cases without realizing it. TA data is not preserved forever. Carrier retention is shockingly short:

• Verizon: ~7 days

• T-Mobile: ~30 days

• AT&T: ~13 months

If you don’t request TA immediately (or send a preservation letter in time) those values may be gone forever. This is one of the biggest hidden pitfalls in cellular evidence.

If you learn about an incident too late, TA may already be unrecoverable.

Why Some Sites (Like Outdoor DAS) Require Caution

Not all towers are built the same. Outdoor DAS (Distributed Antenna Systems)—common in dense areas, stadium districts, and shopping regions—can behave differently:

• Multiple small nodes may transmit for the same sector.

• Fiber links between nodes and hubs can add timing delays.

• Mapping TA arcs from the wrong location (node vs. hub) can create errors.

Bottom line: TA is still valuable, but DAS sites require an expert familiar with their design.

Why Timing Advance Matters in Litigation

TA can dramatically strengthen or weaken location-based claims in:

• Criminal prosecutions and defenses

• Accident reconstruction

• Workplace incidents

• Insurance disputes

• Civil liability cases

• Fraud investigations

It can show:✔ Whether a phone could physically be where someone claims✔ Whether a witness’s timeline makes sense✔ Whether a driver was actually near the incident location✔ Whether cell data aligns—or conflicts—with sworn testimony

But none of that is possible if TA is not preserved before it expires.

What Attorneys Should Be Doing Immediately

1. Send a preservation request the moment a case is opened.

   • Specifically mention Timing Advance.

   • Include call detail records with cell site information.

2. Request TA even if you think you won’t need it.

   • You can ignore data you don’t need.

   • You can’t recreate TA once it expires.

3. Ensure your expert knows how to interpret TA.

   • Especially with DAS, small cells, and complex urban deployments.

4. Use TA to build or challenge timelines early.

   • Don’t wait for trial to discover you’re missing a critical measurement.

Conclusion

Timing Advance is one of the most powerful, yet most frequently missed, pieces of cell phone evidence available to attorneys. When used correctly, it can significantly narrow a device’s possible location, support or contradict testimony, and strengthen the factual foundation of your case.

But because TA can expire in days or weeks, attorneys must know it exists, know how to request it, and preserve it before it's gone.

If your case involves cell phone evidence, make sure Timing Advance is part of the conversation from day one.

Kevin R. Horan, J.D. is a retired FBI Supervisory Special Agent and co-founder of Precision Cellular Analysis. He provides expert analysis and testimony on cellular records, tower mapping, Timing Advance, forensic extractions, and digital evidence in civil and criminal cases nationwide.