Does anyone know if these devices are available in Thailand, and how they work. I ask because I often have to call my US bank and their only communication is by telephone. My less than perfect hearing combined with long distance connections sometimes make communication next to impossible. A hearing aid is not an option for me.  These banks do offer the TTY TDD connection. I know little about these devices, but I think you need a land line and then connect the device to it. f anyone has had any experience with this I'd like to know. I can manage now but am concerned if my hearing worsens.

It is a teletype device to send/receive text.  If unable to buy locally perhaps Ebay

https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=tty%2Ftdd&_sacat=0

 

Don't your banks offer online banking?  That would provide the same type of service without telephone costs or special equipment.