Thanks @Dom, you know way more about this than I do so the thread referenced below may share nothing with this current thread except that I do still believe that character encoding issues SUCK!
All my work has been on SIMCOM SIM7000, SIM7500A and soon the SIM7600G R2. I think all the characters I use are in the ASCII set but if you need to me to test with my SIM7500A I can. It sounds like the work you’re doing is in a test env so maybe I can’t help. If you want me to try the char set you included in your last message with my modem I can fairly easily.