Thailand to Laos: Which eSIM for the Crossing, and When to Switch

Most people heading into Laos come from Thailand: over the First Friendship Bridge to Vientiane, on the overnight train from Bangkok, down the Mekong by slow boat from Chiang Khong, or on a short flight to Vientiane or Luang Prabang. Whichever way you come, your Thai SIM stops being useful at the border. This guide covers what to set up before you leave Thailand, and what each crossing means for your phone.

Short answer: buy and install a Laos eSIM while you still have Thai data or hotel Wi-Fi, keep your Thai SIM in the phone, and switch mobile data to the Laos line once you’re through Lao immigration. The plan’s days only start when it first connects in Laos.

Set it up before you leave Thailand

Installing an eSIM needs an internet connection, so do it on the Thai side, not at the border. The QR code and instructions arrive by email within minutes of buying.

1. Check your phone supports eSIM and isn’t carrier-locked.
2. Buy the plan that matches your days in Laos (prices below) and scan the QR code from the email while you’re on Thai data or Wi-Fi.
3. Leave your Thai SIM or eSIM in place. On most phones you can keep two lines: the Thai one for calls and SMS, the Laos one for data.
4. Keep mobile data on the Thai line for now. You’ll switch after the border.

The Laos eSIM is a Lao Unitel line. It can’t connect in Thailand, and the 365-day window to first connect means you can buy it days or weeks ahead without wasting anything.

When to switch to the Laos line

Switch once you’re through Lao immigration, not before. The Mekong is narrow at the main crossings and networks spill across it: travellers on the Tripadvisor Laos forum describe Thai phones picking up signal from the other bank along the river. The same works the other way, so the Laos line can pick up Unitel while you’re still in the Thai exit queue, and its days start from that first connection.

Once you’re stamped in, set mobile data to the Laos line. It connects to Unitel automatically. If it doesn’t, toggle airplane mode, and if needed set the APN to unitel3g.

Crossing by road and bus: Nong Khai to Vientiane

The First Thai-Lao Friendship Bridge between Nong Khai and Vientiane is the busiest crossing. According to Seat61 and several backpacker guides, you can’t walk across: a shuttle bus runs over the bridge roughly every 20 minutes for about 30 baht, with tickets sold just after Thai immigration. Travel guides list the crossing as open daily from 06:00 to 22:00.

From Nong Khai town or station to the border it’s a short tuk-tuk or songthaew ride. On the Lao side you’re about 20 km from central Vientiane. Have the Laos line ready for the ride into town: booking a ride-hailing car or checking the map is where data matters first.

Crossing by train: Bangkok to Vientiane

The direct sleeper from Bangkok has run since July 2024. Seat61 (updated June 2026) lists train 133 leaving Krung Thep Aphiwat at 21:25 and reaching Vientiane Khamsavath at 09:05 the next morning, with a daytime option (train 75) leaving at 08:45 and arriving at 17:55. Immigration for both countries is handled at the stations, and Seat61 reports that Lao eVisas are accepted for train entry at Khamsavath.

Khamsavath is about 7 km from central Vientiane, so you’ll want data on arrival for a taxi or ride-hailing app. Switch to the Laos line after Lao immigration at the station.

Crossing for the slow boat: Chiang Khong to Huay Xai

The Fourth Friendship Bridge links Chiang Khong to Huay Xai, the start of the two-day Mekong slow boat to Luang Prabang. Backpacker guides report a shuttle across the 2.5 km bridge for 20 baht at standard times, and that since December 2024 the slow boat leaves Huay Xai at 9:00, so most travellers now spend the night in Huay Xai or Chiang Khong first. Check current entry rules for your nationality before relying on this crossing: Backpackers Wanderlust reports that since October 2025 some passports can’t use this checkpoint.

Switch to the Laos line in Huay Xai. On the river itself, signal comes and goes: you’ll get it near villages and around Pakbeng, the overnight stop, with long gaps between. Our slow boat internet guide covers what to download before you board.

Crossing in the south and centre

• Chong Mek to Vang Tao (for Pakse): a direct bus runs from Ubon Ratchathani to Pakse in about three hours, according to Asia for Visitors. Switch lines after Lao immigration at Vang Tao.
• Mukdahan to Savannakhet (Second Friendship Bridge) and Nakhon Phanom to Thakhek (Third Friendship Bridge): the same rule applies. See our Savannakhet connectivity guide for coverage once you’re across.

Flying in from Bangkok or Chiang Mai

There are direct flights from Bangkok to Vientiane and Luang Prabang, and from Chiang Mai to Luang Prabang (flight-search listings show Lao Airlines and Bangkok Airways on the Luang Prabang routes). Install the eSIM before you fly, keep it switched off for data during the flight, and switch to it when you land. It connects on arrival, so you can sort transport from the terminal without looking for a SIM counter.

Which plan to choose

All Laos plans run on Unitel and are data only:

• 10GB, 10 days: $6.90
• 15GB, 15 days: $7.90
• 20GB, 30 days: $8.90
• 30GB, 30 days: $9.90

Going on from Laos to Vietnam or Cambodia? The Indochina plan covers Laos, Cambodia and Vietnam on one eSIM. It doesn’t include Thailand. If your trip loops back into Thailand, keep a Thai line for that part; our Laos and Thailand eSIM guide compares the options for a trip through both.

If the Laos line doesn’t connect

1. Check mobile data is set to the Laos line and that line is switched on.
2. Toggle airplane mode on and off.
3. Set the APN to unitel3g if your phone didn’t set it automatically.
4. Dial *122# on the Laos line to check your data balance.

Still stuck? Write to support@internetlaos.com with your order number and a screenshot of your mobile-network settings.