sending ussd

[bahao113]

Hello sir, thank you a lot for this useful code. My device named Olax U90, another version of MF823. I can't send sms with my interface because the producer break hide or break it in web interface, but i can send SMS with your code.
My problem is USSD, i tried to send USSD but the web interface say "USSD unsuported", the ussd_write_flag is 99 after 15. I read somewhere say it's band have to be WCDMA to send USSD, but i can't send because band is alway LTE
even though I switched it to WCDMA only mode.
Can you help me with USSD, I really appreciate your code.
Thank you a lot for reading my Issues!