Any suggestions greatly appreciated. I want to call on normal phone service….not internet etc?.

Skype Out is what  I use for calling home (UK).

 

https://www.skype.com/en/international-calls/Australia

I use MyTello, which sets up a Bangkok based number that is directed through the internet to wherever you want. 0.4 baht per minute plus local call charge depending on your provider deal.

https://app.mytello.com/en/

Not claiming it is the cheapest but AIS has an international service 003 for 2.5 baht/min for calls to USA.  May be cheaper to Australia. 
 

they must activate first, then just dial 003 and country and area code and number. 
 

just call direct from mobile.