Hey there,

I am having a problem with my phone (Samsung Galaxy S 2) and my AIS 12call sim card, which keeps switching into roaming mode and so loses all data connection.

I am running a custom firmware, but also tried changing the modems, which doesnt change anything... I did have the

same problem with my older phones, but I think not that much.

Is there any known fix for that? I already changed my sim card (made a new one, not new number) ~6 months ago, with no effect.

Do I need a new phone number then? Or can anybody tell me your modem version if you have a fine working Galaxy S 2 in Thailand?

Thanks in advance

Edited December 21, 201114 yr by lupusdom

Wifey has exactly the same problem using ais. She is using a gsm1800 sim and according to our local ais shop is a consequence of that sim and package.

Her previous sim was gsm advance. This had no problems with roaming.

Does your phone roam all the time? In many different locations? Has this happened for a long time, or is it something new?

AIS and TOT have a 3G roaming agreement, as of October of this year, so when you are in a location which does not have AIS 3G you will roam onto TOT's 3G network.

I guess you could disable 3G/2100 Mhz, and select 900 Mhz 3G only. (This assumes your custom ROM kept the original Samsung Service Menu app.)

Not sure if this is correct... get into service mode its the *#*#197328640#*#* then i went to 1 debug mode) option 8 Phone Control option 7 Network Control and 2 Band selection

Thanks to apetley I was reading about AIS's GSM1800 service, operated by a subsidiary DPC. Further AIS is using a portion of the DPC 1800 MHz frequency to test LTE/4G, or may do so in the near future.

lupusdom, are you using the AIS GSM1800 service? If so I would try a normal One-2-Call SIM just to see if you have the same issues. If you don't then maybe ditch GSM1800, even if it means losing your number. Or maybe ask AIS if you can port from GSM1800 to AIS GSM900? And do you have a mobile broadband data plan?

Had the same problem when visiting Bangkok

Posted 2011-09-20 12:00:11

I was in Bangkok couple a days ago and ais gprs/edge didn't worked at all. Or yes it worked but I was many times connected to GSM 1800, not TH GSM and my aircard shows roaming. And when this happened, data would not move. Manual network selection solved the problem.

It's happening to me as well on my SG S2 and I have standart 1-2-call sim however it doesn't drop data as you say, there is an option in settings to use data while roaming so check it in.

Thats the odd thing - I turned data roaming on, and it still loses data connection.

I think I will try to get a new Sim, no matter what and try again. In the store I was just told that the problem should vanish by itself -.-

Thanks so far

I would try a One-2-Call pre-paid SIM to see if you have the same issue.

It would be nice to understand the history of this problem for you; Does your phone roam all the time? In many different locations? Has this happened for a long time, or is it something new?

Lastly, revert to stock and see if you still have the problem; it's all about eliminating possibilities to arrive at a potential cause and solution.