when you open a bank account you can choose to register promptpay with your phone number. That number is then linked to your account. That's why Promptpay works. You can't use the same number if you want to setup promptpay in another bank. I have Bangkok Bank with promptpay. When I opened an account in Krungsri I could not register Promptpay with the same number. When I checked the registration of my number I saw it was already registered in Bangkok Bank. A clever system. You could have used QR payment if the receiver had not registered PromptPay
in your first answer you said incorrect to the statement that an onward travel ticket is necessary and your "proof" was that you were not asked . That was what I answered to. And incorrect it was not because some airlines require it. I see you have modified your opinion after this.
you have proved nothing only because it worked for you. Prove of onward travel is required by a number of airlines. I have been asked by SAS KLM Thai Airways - not every time but they do ask
I have to comment on this again. It is so strange. I was supposed to leave Thailand sep 1 which is 3 months after my arrival. The officer stamped under consideration and I must return October 1! This I consider overstay 1 month. I discovered it late at home yesterday and wrote to them on Line saying I would be overstaying and shouldn't it be sep 1 I should get my visa. The answer today was OCT 1 and it seems I will not be overstaying since he referred to the stamp. Ever heard of this???​