AIS vs DTAC vs TrueMove: Best Coverage for Thai Islands

For travelers heading to remote Thai islands like Koh Lipe or the Similan Islands, AIS generally offers the most consistent coverage, while the combined TrueMove and DTAC network provides excellent high-speed 5G in popular hubs like Phuket and Koh Samui. If you are island-hopping, choosing an eSIM that utilizes these major networks ensures you stay connected without paying the steep roaming fees charged by home carriers like Telstra or Optus.

The Big Three: AIS, DTAC, and TrueMove

Thailand’s mobile landscape is dominated by three major players: AIS, TrueMove H, and DTAC. For years, AIS (Advanced Info Service) has been regarded as the premium provider, often compared to Telstra in Australia for its extensive reach into rural areas and distant coastlines. TrueMove H and DTAC recently merged to form a single entity, significantly expanding their shared infrastructure and closing the gap in coverage.

When you see plans from Thai Simcard, you are accessing these tier-one networks. Our eSIMs utilize TrueMove H (5G), DTAC (5G), and AIS (5G) to ensure that whether you are in a Bangkok skyscraper or a beach hut in Krabi, you have a signal.

AIS: The Coverage King

AIS has historically invested the most in infrastructure for remote areas. If your itinerary involves deep-sea fishing, diving trips far offshore, or staying on less-developed islands like Koh Tarutao, AIS is frequently the only provider with a steady signal. Their 5G rollout has also been aggressive, covering a large percentage of the population.

TrueMove H and DTAC: The Powerhouse Duo

Since the merger, the combined network of True and DTAC has become a formidable competitor. TrueMove H was already known for having the fastest 5G speeds in urban centers like Bangkok and Chiang Mai. By integrating DTAC’s towers, they have improved their reliability on the islands. For most backpackers visiting the 'Big Three' islands (Samui, Phangan, Tao), the True/DTAC network is more than sufficient for streaming, uploading Reels, and using navigation apps.

Island Hopping: Who Wins the Coverage War?

Coverage on the islands is a different beast compared to the mainland. The limestone karsts and hilly terrain of places like Koh Phi Phi can create 'dead zones' for weaker networks.

Region	Best Carrier	Reliability
Phuket & Koh Samui	All (True/AIS/DTAC)	Excellent 5G
Koh Tao & Koh Phangan	AIS / TrueMove	Very Good
Koh Lipe & Far South	AIS	Good
Koh Chang & Eastern Islands	AIS / DTAC	Very Good
Similan & Surin Islands	AIS	Moderate (Near Shore)

The Gulf of Thailand: Samui, Phangan, and Tao

In the Gulf, you will find excellent connectivity. Even at the Full Moon Party on Koh Phangan, the networks are robust enough to handle the surge in data usage. Koh Tao, being further out, used to have spotty service, but now features strong 4G and 5G coverage near Sairee Beach and the main piers. If you are staying on the quieter side of the island (like Tanote Bay), AIS tends to hold a signal slightly better behind the mountains.

The Andaman Sea: Phuket, Phi Phi, and Lipe

Phuket is effectively a mainland province in terms of tech; you will get 5G almost everywhere. Koh Phi Phi is also well-covered due to its high tourist density. However, as you move toward Koh Lipe near the Malaysian border, the signal can fluctuate. AIS remains the most reliable here, though TrueMove H has improved significantly.

Why Australian Travelers Should Skip Roaming

For many Australian backpackers, the temptation to simply leave their Telstra or Optus SIM in and pay a daily roaming fee is high. However, these fees add up quickly over a two-week or month-long trip. More importantly, roaming data is often 'deprioritized' by local Thai towers, meaning you might have a signal but agonizingly slow speeds.

By using a travel eSIM, you connect directly to local Thai towers as a primary user. This is not only cheaper but provides a much more stable connection for essential tasks. For a deep dive into the costs, read our guide on Data Roaming vs eSIM: The Cheapest Way for Aussies to Travel.

Buying at the Airport vs. Thai Simcard

Arriving at Suvarnabhumi (BKK) or Phuket (HKT) airports, you will be greeted by rows of brightly lit kiosks. While convenient, these kiosks often have long queues and higher 'tourist' pricing for limited plans. Furthermore, airport staff are often in a rush, which can lead to configuration errors on your phone.

Ordering an eSIM from Thai Simcard before you fly allows you to hit the ground running. As soon as your plane lands and you turn off airplane mode, your phone connects to the local network. This is vital for booking a Grab or Bolt to your hotel, as the airport Wi-Fi can be notoriously difficult to join without a local SMS verification.

Integration with Grab and Food Apps

One of the biggest advantages of having immediate data is the ability to use Southeast Asia’s 'super-apps.' Grab and Bolt are essential for avoiding the 'mafia' taxi prices at island piers. While our plans are data-only and do not come with a local phone number, they work perfectly with these apps.

Most travelers already have a Grab account linked to their Australian or international number. You can continue to use that account over the data connection provided by your eSIM. You can also use WhatsApp, Messenger, and FaceTime to make calls to home or local businesses without needing a traditional voice line. If you find yourself staying longer than expected, you can learn How to Extend Your Thai Tourist SIM for Another Month to keep your data flowing.

Installation Guide for iPhone and Android

Setting up your eSIM is a digital process that takes less than five minutes. Before you start, ensure you check your phone compatibility to confirm your device is eSIM-ready.

For iPhone Users:

1. Go to Settings > Cellular (or Mobile Data).
2. Tap Add eSIM.
3. Select Use QR Code and scan the code sent to your email by Thai Simcard.
4. Label the new plan as 'Travel' or 'Thailand'.
5. Set your 'Cellular Data' to the new eSIM, but keep your 'Default Voice Line' as your primary Australian SIM if you need to receive urgent SMS (just ensure data roaming is OFF for your Australian SIM).

For Android Users:

1. Go to Settings > Connections > SIM Manager.
2. Tap Add eSIM or Add Mobile Plan.
3. Scan the QR code provided.
4. Once downloaded, ensure the Thai eSIM is selected for 'Mobile Data'.

For a more detailed walkthrough, visit our easy setup guide.

Choosing the Right Data Plan

Your data needs depend entirely on your travel style. If you are a digital nomad working from a cafe in Koh Samui, you will need a high-allowance plan. If you are just using Google Maps and WhatsApp, a smaller plan is sufficient.

• Light Users (1GB - 5GB): Perfect for short stays or those who rely on hotel Wi-Fi. Available in 7-day to 30-day durations.
• Heavy Users (10GB - 50GB): Ideal for long-term backpackers or those who stream music and video on long ferry rides between islands. We offer 50GB plans that last up to 180 days for those on an extended gap year.
• Daily Pass Users: If you want unlimited-style access, our daily passes provide high-speed data (0.5GB to 10GB per day) followed by a throttled speed to keep you connected until the next day resets.

All Thai Simcard plans are data-only and do not include a local phone number, making them a streamlined choice for the modern traveler. If you run out of data while lounging on a beach, top-ups are available to get you back online instantly.

The bottom line

While AIS holds the title for the best coverage in the most remote corners of the Thai islands, the TrueMove and DTAC merger has created a high-speed network that is more than capable for 95% of travelers. By choosing a travel eSIM from Thai Simcard, you avoid the high costs of Australian roaming and the hassle of airport kiosks. Whether you need 1GB for a quick trip to Phuket or 50GB for a three-month island odyssey, see plans today to ensure you stay connected from the moment you touch down.