we recently bought iMobile IQX3, dual SIM, but the phone allows only one SIM to work on 2100 MHz (you can choose in the settings which one).

As SIM1 we use a DTAC Trinet card, we use it for Internet on 2100 MHz.

In the second SIM slot we put a 2100 MHz 12call card. It shows permanently an R for roaming (as is expected because it uses the old network of AIS, not 2100 MHz).

Unfortunately, AIS will very often have no signal at all. The signal will disappear and come back after 20 min up to 3 hours.

Location is in Nonthaburi, in central Bangkok AIS works.

When we put the AIS SIM in another phone in Nonthaburi it works flawlessly.

We got a new AIS SIM in the Serenade Shop in Paragon and a software update of the phone in the iMobile service center in MBK, all to no avail.

BTW both iMobile staff and AIS staff were extremely incompetent (as opposed to DTAC staff)

iMobile staff told us it is a cheap phone so why do you expect it to work?

Might the roaming be the problem?

How can I confirm this, and what would be a solution?

Does any provider still offer SIMs that are not 2100 MHz and that we may use as second SIM? True move?

And any idea how to find a competent person at AIS? I have always had only bad experiences with their Serenade center in Paragon. Their call center is usually ok, but this problem seems too difficult.

thanks a lot for any help

Not sure what you are expecting. Are you saying you want 3G to be available on both sims at the same time? If so that can't happen.

Most other phones only give a 3G connection in one of the sim locations so you have to physically swap the sims over.

3G is available in both sim locations on I-mobile IQ series phones but you have to tell the phone in settings which sim you want to use on 3G and the other one automatically shows roaming. I have an IQX2 and an IQX and, while I was waiting for the house internet to be connected I had both AIS and DTAC sims in the one phone and, as well as basic surfing, I mainly used the 3G on each sim to stream the EPL football. When I'd used up my AIS 3G speed allowance I would just switch to DTAC for 3G in the phone settings to use DTAC's 3G.

But you have to choose which one you want to use, you can't have 3G available/active on both sims at the same time.

thank you

what you decide is exakt what i want and what i am expecting

I am happy to hear that i dont have some misunderstanding here

what happens is that with the AIS SIM in slot 2 and using DTAC for Internet (3G) the AIS signal FOR VOICE CALLS will disappear very often, for hours at a time.

I want to use AIS for voice calls, DTAC for 3G, but voice calls often get cut off or there is no AIS signal to make a voice call.

thank you

what you decide is exakt what i want and what i am expecting

I am happy to hear that i dont have some misunderstanding here

what happens is that with the AIS SIM in slot 2 and using DTAC for Internet (3G) the AIS signal FOR VOICE CALLS will disappear very often, for hours at a time.

I want to use AIS for voice calls, DTAC for 3G, but voice calls often get cut off or there is no AIS signal to make a voice call.

Yes, I'd forgotten about that. It's not ideal, but (probably) better than physically switching sims over into different slots all the time.

Slot two (AIS?) is the primary slot so, when using 3G from that sim, the sim in slot one (DTAC?) works normally for voice calls, messaging etc and, although showing as roaming, doesn't incur any roaming charges.

If you want to use DTAC (slot one) for 3G it simply means switching the 'data connection in settings........but it also switches the AIS (slot two) sim off completely. Reverting to AIS for your data connection automatically switches the AIS voice calls back on as well.

For me it wasn't a big problem anyway. I had a similar setup to you and used AIS as my primary sim for calls and data. When my 3G speed was used up the slower speed was good enough for general surfing, emails, etc and I only switched to DTAC to use their 3G to stream football. It did mean the AIS sim was off but that simply meant nobody could phone and disturb me during the match . After the football I'd simply turn the AIS data back on.

Incidentally, if you're outside an AIS 2100MHZ area it automatically switches to the old 900MHZ signal and, again, shows as roaming on the phone, but doesn't incur any roaming charges.

thanks again

very helpful in understanding how dual SIM phones from iMobile are supposed to work.

We actually bought 2 IQX3, and the second one now developed the same problem: the signal for voice calls with SIM 2 sometimes drops (AIS in both phones) and comes back again. Not in central Bangkok, but in places where the signal a bit weaker than in central Bangkok.

And only if you make a lot of phone calls.

Technology is something weird. ..