I need help use 4G Quectel EC20F

I use Ec20 4G. I use USSD . AT+CUSD=1,##002# and AT+CUSD=1,**21*Phonenumber# . it respon OK but it returned ok but it didn’t work

Hi customer,

  1. Please send ATI and keep result for me.
  2. Could you please confirm if your SIM card supports USSD or not with operator?