How can i store GSM balance/credit report

Ive been programing my Gsm modem to store balance/credit reports from the carrier without success. im writing a program that must store the information to modem memory, im using hyperterminal to test commands and i would recharge the modem SIM with airtime, but the sms confirmation cannot download in to SR. I not sure if its possible at all. I tried all combinations of AT+CNMI I use Huawei e160 usb modem which has SR memory. Any help will be greatly appreciated.