AIS or DTAC: Which Mobile Network Is Best on the Thai Islands?
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Short answer: AIS is the safer choice if you're hopping between islands, visiting smaller islands like Koh Tao, Koh Lipe or Koh Lanta, or need signal on the ferries. DTAC performs very well in the main tourist areas of Koh Samui, Koh Phangan and Phuket. Our Thailand eSIM works on both networks, so you're covered either way.
Thailand is one of the most popular travel destinations in the world, especially the islands in the south such as Koh Samui, Koh Phangan, Koh Tao and Phuket. One of the most common questions before the flight is which mobile network is best for an eSIM: AIS or DTAC. In this guide we lay out the real differences between the two networks, area by area, so you arrive with the most stable connection.
Worth knowing: our eSIM for Thailand runs on both AIS and DTAC. Your phone connects automatically to the strongest available network, and you can also choose a network manually in your phone's network selection settings.
Background: Thailand's two big networks
Thailand's mobile market today effectively has two main players: AIS, which remained independent and holds the largest market share, and DTAC, which merged with TrueMove H in 2023 to form a joint company called True Corp. In practice, DTAC SIMs are still active and sold separately, but their infrastructure is increasingly integrated with the True network.
AIS: the strongest network on the islands and in rural areas
AIS is considered the network with the widest coverage in Thailand, especially in rural areas and on smaller, more remote islands. This shows in a few key ways:
- Coverage between islands and on ferry crossings: AIS keeps better signal along most of the ferry route between Koh Samui and Koh Phangan, while other networks tend to "drop" in the middle of the crossing
- Small, remote islands: on Koh Tao, Koh Lipe and Koh Kood, AIS is clearly the leading network
- Inland roads and hills: even away from the coast, such as Koh Samui's southern ring road or the hilly interior, AIS stays more stable than its competitors
DTAC: a strong alternative on Koh Samui and Koh Phangan
DTAC is often seen as the "under the radar" network, but in practice it performs very well in specific areas:
- Koh Samui and Koh Phangan: DTAC works especially well in the main tourist areas such as Chaweng, Bophut and Lamai on Koh Samui, and the main beach areas on Koh Phangan
- Phuket: in the towns and main beaches (Patong, Kata, Karon) DTAC works well, but weakens somewhat in the hills and less populated parts of the island
- Budget: DTAC is usually considered the more affordable of the two
However, DTAC is noticeably weaker on islands such as Koh Tao, Koh Lanta and Phi Phi, and less reliable on rural routes or long roads outside the tourist centers.
Comparison table by destination
| Destination | AIS | DTAC |
|---|---|---|
| Koh Samui (main tourist areas) | Excellent | Very good |
| Koh Samui (southern ring road / hills) | Excellent | Coverage gaps |
| Koh Phangan | Excellent | Good |
| Koh Tao | Very good | Relatively weak |
| Phuket (main beaches) | Excellent | Good |
| Phuket (beyond the resort strip) | Very good | Average |
| Phi Phi / Koh Lanta | Good | Weak |
| Koh Lipe / Koh Kood | Clearly the leading network | Not recommended |
| Ferry crossings between islands | Keeps signal for most of the crossing | Tends to drop midway |
So which network should you choose?
If you plan to move between several islands, including smaller ones like Koh Tao, Koh Lipe or Koh Lanta, or if a stable connection on the ferries matters to you, AIS is the safer choice.
If you're mostly staying on Koh Samui or Koh Phangan and don't plan to leave the main tourist areas, DTAC performs very well.
If you're undecided, AIS is usually the safer choice for overall coverage, especially if your route includes more than one island.
Frequently asked questions
Is DTAC enough for a trip to Koh Samui only?
Yes. In most populated and touristy areas of Koh Samui, DTAC gives a very good connection, with almost no noticeable difference from AIS.
What if I move between several islands on the same trip?
In that case AIS is the better pick, because it keeps more consistent coverage on small islands and during ferry crossings.
Is data speed very different between the networks?
In most tests AIS shows higher average speeds, especially in rural areas and on remote islands, while in the cities and main tourist areas the difference is much smaller.
Which network does your Thailand eSIM use?
Our Thailand eSIM runs on both AIS and DTAC. Your phone connects automatically to the strongest network, and you can switch manually in your network selection settings if you prefer one of them.
Summary
There's no single right answer for everyone: if your route includes small islands, island hopping or remote spots like Koh Tao and Koh Lipe, AIS gives the most stable coverage. If you're mostly staying on Koh Samui or Koh Phangan, DTAC is an excellent alternative. For everything else about getting connected, read our Thailand SIM card guide for tourists, or go straight to the eSIM plans for Thailand.