Im using samsung galaxy note 2 and been using AIS Travellers sim for the last 2 months. Last week I went to Laos for a week and came back today. When I got to Nong Khai border around 2:30pm I was still able to use my phone's mobile data and I was still able to text and call. I then turned my phone off to save battery as I was still on the bus. After getting to Udon Thani around 3-3:30pm that's when the phone stops working. I tried putting another sim and same problem.

Anyone who experienced this? Were you able to solve it? If so, how?

I have a note 2 and this has happened a couple of times. Each time i restarted the phone and it came back. You must re-power, not just turn the phone off to a blank screen.

What Mobi posted -- Shutdown, count to 5, power back up -- allows the phone to reinitialize

If that doesn't reacquire AIS, then assuming you have a SIM that is still active,

System Settings > More... > Mobile Networks

Network Mode : Select 3G

Network Operators > Search Networks (to see if the radios detect any services), if so, go back and...

Network Operators > Choose automatically

If the phone still balks, try Network Operators > Search Networks

and select any one of the following if available:

AIS 3G

TH GSM 2G

AWN

520 03

You may have to wait until you reach another group of AIS Towers before the system recognizes you and "Choose automatically" works correctly.

My best guess is that you may have been roaming in Laos (Laos Telecom), and you retained that APN setting. Some phones/ROMs handle the flushing of APN details better than others.

You can always go to Settings, About Phone, Status to get a clear picture of the currently registered network.

If you cannot register on a network, simply power down the phone, remove the battery, remove the SIM, re-insert the SIM, re-insert the battery and restart the phone. The APN details are baked in to the SIM, and should automagically configure (for most phones), register and connect to the AIS network.

You can check at Settings, Wireless and networks, Mobile networks, Access Point Names.

Yup. Complete POWER OFF, short wait and restart.

Both myself and GF had issues in Nong Khai a while back with our phones, for no apparant reason, latching onto a Laos telecom provider rather than AIS. And we were in Nong Khai at the time, not Laos.

I had a similar problem with AIS after "Roaming".

AIS block the APN (ability to log on to their network) to stop you running up a big bill ).

I rang them and they cleared the blockage and I was logged on again straight away.

I did all the suggestions above. Power off, removed battery and sim for an hour to no avail. Went to AIS last night and they cannot do anything. Taken it to a phone shop today and the guy said something is wrong where the sim is placed as even other sims from other network doesn't work. The guy will to fix it for 1500 baht. Not sure if I did the right thing but not having a phone in a foreign country is not what I wanted.