When I do 'ATD*99***1#' in Hyperterminal I get an error message.

- Set AT+CMEE=1. Then try again to see what CME error is shown. Check the CME error in the Reference Guide.
- Make sure the APN is programmed correctly into the modem by sending 'AT+CGDCONT?'.
- Check 'AT+CGCLASS?' If it returns anything other than "B", change it to "B" by setting 'AT+CGCLASS="B"'.
- Make sure that you have GPRS (packet switched data) service.