I cannot currently receive TrueMoveH text messages when in the UK.     I've tried with TrueMoveH web login and  Kasikorn banking, both of which should send me a text message.

 

On the TrueMoveH app, I have the roaming settings to receive calls and data ON.    There is no separate setting for SMS.
 

What is the likely cause of this problem ?

 

[Without SMS messages, I cannot login to the TrueMoveH website or make payments from my bank account website.

I can do both via the respective apps, still installed on my old phone. ]

Have you turned on roaming on your mobile telephone? You will need to do this to receive TruemoveH SMS. It sounds illogical as you are within the UK and you are not roaming - but it is necessary.

 

What I do is before I need to receive an SMS I turn off mobile data on my mobile phone, then I turn on roaming on my mobile phone. I request the SMS, then once I have received it I turn mobile roaming off on my mobile telephone and turn mobile data back on.

 

It sounds the wrong way of doing it, but give it a try.

Well, after a little more testing I solved that problem:

 

The Thai SIM does not receive incoming text messages (or show any sign of a connection) in my Nokia 1661 phone, but DOES receive them in on a newer Android phone
My UK SIM receives incoming text messages in both phones.  

 

I don't quite know precisely why this fails, but suspect my 2018 Thai SIM is not compatible with the older phone, whilst my 2023 UK SIM is.  

 

I find the Nokia is very convenient for receiving 2FA text messages on my UK SIM in Thailand & other countries.   It's small, has a long battery life and boots up quickly. 
Unfortunately, reversing that process and putting my Thai SIM in the Nokia in the UK fails.

 

Naturally I use a smart phone for my main SIM, whatever the country.      One day I must look into e-sims.

 

6 hours ago, jaizan said:

I cannot currently receive TrueMoveH text messages when in the UK.     I've tried with TrueMoveH web login and  Kasikorn banking, both of which should send me a text message.

 

On the TrueMoveH app, I have the roaming settings to receive calls and data ON.    There is no separate setting for SMS.
 

What is the likely cause of this problem ?

 

[Without SMS messages, I cannot login to the TrueMoveH website or make payments from my bank account website.

I can do both via the respective apps, still installed on my old phone. ]

Call yourself to see if calls come through. If the phone rings, then manually search for another network other than the one you are currently using. Mobile data can be on but Data Roaming should be off. 
I don’t understand your last sentence.