TrailSim coverage glossary

TrailSim reports use a small, fixed vocabulary so that a figure on one route means the same thing on another. The definitions below are the ones the model actually applies. Each term has its own anchor, so you can link straight to it. For the full method, read how it works; to see the terms in use, open the Coverage Index or any of the route pages.

Usable 4G/5G data (also called fast data)

A sampled point on the route where the plan's networks are modelled to provide 4G or 5G. In practice this means maps load, messages send with attachments, and calls over data work. The percentage on a route page is the share of sampled points in this class.

2G/3G only (slow data)

The amber tier: a sampled point with signal but not fast data. On routes modelled from OpenCellID it means only 2G or 3G towers reach the point — texts and simple messages usually get through, map tiles and photo uploads often do not. On routes modelled from FCC filings (United States) or Ofcom drive tests (United Kingdom) the same tier is labelled weak 4G: 4G signal below about −100 dBm, bars but barely usable data — the United States switched 3G off in 2022. Where a country has retired 2G and 3G, the legacy class does not appear.

No signal

A sampled point where none of the networks the plan can use is modelled to reach at all. Emergency calls may still work on another carrier's network, but the eSIM's data will not.

Not surveyed

A stretch the underlying measurement survey never visited, such as roads Ofcom's drive-test vehicles did not drive. It is shown as unknown, never as no signal, and is left out of the coverage percentages.

Dead zone

A continuous stretch of route 2 km or longer with no signal on the plan's networks. Shorter gaps are counted in the no-signal percentage but not listed as dead zones. Each dead zone in a report is named, measured and marked in the PDF and GPX.

Stage

A section of the route in the report tables — not a day's travel. On trails, stages run between named places (Milngavie → Drymen); on long road and cycle routes they are fixed 25 km coverage segments, so Route 66 has 139 of them. Plan your days from the distances, and read the stage figures as "this stretch", not "this day".

Best network / network combination

The set of carrier networks a given eSIM plan can use on a route. Because coverage is modelled for each carrier separately, plans with different roaming partners score differently. The "best" combination is the one, among those on offer, that covers the most of the route; Coverage Index figures use it.

Our Pick

The featured plan on a route page. It follows the sizing rule of at least 500 MB per day and balances coverage with price, so it can sit slightly below the highest-coverage combination. The map on the route page updates to whichever plan you select.

Coverage report

The route's analysed coverage in three forms: a web page with signal percentages and a dead-zone list, a printable PDF map, and a GPX file with the route and dead-zone waypoints. On routes that have one it is included with every order and delivered by email with the eSIM.

Mountain upper-bound estimate (tower-position model without terrain)

On mountain routes the model places towers and their range but does not account for ridges and valleys blocking the signal. The figure is therefore an upper bound: real coverage can only be equal to or worse than what is shown. Routes using it say so and print "up to" before the percentage.

Data source (the four sources)

The public dataset a report is built from, chosen per region: OpenCellID crowd-sourced tower records for most of the world; the FCC National Broadband Map carrier filings for US routes; Ofcom drive-test measurements for some UK routes; and the ACMA licence register of carrier transmitter sites for Australian routes. Every report names its source and says what kind of evidence it is.

Sample / 500 m sampling

The route from OpenStreetMap is divided into points every 500 metres. Each point is classified separately for each carrier as usable 4G/5G, 2G/3G only, no signal or not surveyed. All percentages and dead-zone lengths are built from these points.

Days start on first use

A plan's validity period begins the first time the eSIM connects to a network, not when you buy it. Buying weeks before a trip is safe.

Pay by the day (daily plan)

A plan priced per day rather than per data bundle, with a daily full-speed allowance of 300 MB to 1.5 GB. You choose 1 to 90 days at checkout, with the route's typical trip length pre-filled. Offered on routes where the wholesale catalogue has it, shown below the fixed plans.

Throttled / fair-use policy

Slowed rather than cut off. On TrailSim's daily plans, once the day's full-speed allowance is used the connection continues at a lower speed until the day resets. Fixed-data plans are not throttled; they stop when the data is used up. Other sellers' fair-use rules are on their own sites.

Multi-network eSIM

An eSIM plan that can roam onto more than one carrier network in the same country. On a route this matters because the phone can pick whichever partner network reaches a given point, so the plan's coverage is the union of its networks.

Coverage Index

TrailSim's public ranking of every analysed route by usable 4G/5G share, with dead-zone counts, at /coverage-index. It is open data under CC BY-SA 4.0, also available as CSV, and free to cite and republish with attribution to TrailSim.