Which eSIM survived the islands: a field report

Testing an eSIM where signal usually struggles

Islands are where mobile coverage claims go to die. Fewer towers, more water, and terrain that blocks signal all conspire to make an eSIM that looks great in the city struggle the moment you reach a beach or a pier. So we took a travel eSIM around Koh Yao Noi, a quiet island in Thailand's Andaman Sea, and tested it at real spots: a hotel, a beach, a pier, a cape, and the island's rice fields. This is the honest report of what held up and what slowed down.

The headline is reassuring: at every single spot we tested on the island, the eSIM kept a working 5G signal. Not one location was a dead zone. What changed was speed, and it changed a lot, from a low of 17.9 Mbps at a quiet pier to a high of 109.57 Mbps out in the rice fields, which surprised us. The lesson is that island coverage is real but uneven, so where you stand matters more than which island you are on.

What we measured, spot by spot

The spread across a single small island is the real finding. The fastest reading was Koh Yao Noi Rice Fields at 109.57 Mbps on TrueMove H, genuinely fast for open countryside. Koh Yao Noi Long Beach gave 82.7 Mbps on AIS, and the Koh Yao Noi 6 Senses Hotel returned 71.1 Mbps, both perfectly comfortable for streaming and calls. Off the island but still in the water, our Phuket Andaman Sea test hit 70.3 Mbps, which is remarkable for a boat reading over open sea.

The slow spots tell the other half of the story. Koh Yao Noi Cape Kudu dropped to 46.5 Mbps and Koh Yao Noi Paradise Hotel to 30.7 Mbps, both still usable. The lowest was Koh Yao Noi Tha Khao Pier at just 17.9 Mbps, slow enough that a video call would struggle but fine for maps, messaging, and loading a ferry schedule, which is exactly what you need at a pier. Nowhere did the signal disappear; the island's weak spots were slow, not dead.

AIS and TrueMove H on the island

Two networks carried our island tests: AIS and TrueMove H. Interestingly, TrueMove H produced the island's fastest reading, 109.57 Mbps in the rice fields, and held a solid 71.1 Mbps at the hotel, though on a small island sample of 3 tests we would not rank it definitively. AIS carried the widest spread, from 82.7 Mbps at the beach down to the 17.9 Mbps pier reading, consistent with its behaviour across Thailand as a whole.

For a traveller, the practical point is that both networks kept the island online, so the choice between them mattered less than where you happened to be standing. The same physical spot, a sheltered pier versus an open field, made a bigger difference to speed than the operator did. If your travel eSIM uses either AIS or TrueMove H on a Thai island like this one, our tests suggest you will have a working connection, fast in the open, slower in the tucked-away corners, but present throughout.

What this means for island travel

If you are heading to a Thai island with a travel eSIM, plan for variable speed rather than no signal. Our Koh Yao Noi tests ranged from 17.9 to 109.57 Mbps and never dropped out, which means everyday tasks, maps, messaging, booking a ferry, checking in, worked everywhere, while heavy streaming was comfortable in the open spots and better saved for the hotel wifi at the slow ones. That is a very usable island experience, and better than many travellers expect.

The broader lesson from measuring an island directly is that coverage fear is often overblown, but speed variation is real. Rather than worrying whether an eSIM works on an island at all, assume it will connect and plan your heavy tasks around the faster spots and your accommodation wifi. These island readings feed into our Mobile Speed Index alongside our city tests, so you can see how a destination scores overall, remote corners included, before you go. The tools link below has the full picture.

Frequently asked questions

Does a travel eSIM work on Thai islands?

In our tests on Koh Yao Noi, yes, at every spot. The eSIM kept a working 5G signal from the beach to the pier to the rice fields, with no dead zones. Speeds ranged from 17.9 to 109.57 Mbps, slower than the city but always usable.

How fast is mobile data on a Thai island?

Variable. On Koh Yao Noi we measured 17.9 Mbps at a quiet pier up to 109.57 Mbps in the rice fields. Open areas were fast enough for streaming; tucked-away spots like the pier handled maps and messaging but not much more.

Which network is best on Thai islands?

Both AIS and TrueMove H kept our island online. TrueMove H gave the fastest island reading at 109.57 Mbps, but on a small sample. In practice, where you stand mattered more than which network, since a sheltered pier was slower than an open field on either.

Will I lose signal on a remote island?

We did not, anywhere on Koh Yao Noi across our tests. The weakest spot still returned 17.9 Mbps, enough for navigation and messaging. Plan for slower speeds in remote corners rather than no signal, and save heavy streaming for faster spots or hotel wifi.

Can I stream video on a Thai island eSIM?

In the faster spots, yes. Readings like 109.57 Mbps in the rice fields and 82.7 Mbps at the beach handle streaming comfortably. At the slowest pier reading of 17.9 Mbps, stick to maps and messaging and save video for hotel wifi.