I'm testing with Sprint using the MTCBA-C-EN modem (for Sprint). However, when I try to retrieve the current MDN and MSID using the commands (AT+WMDN?) and (AT+WIMI?), I get an error.

In order for AT+WMDN? and AT+WIMI? to work you must issue AT+WSPC=1,xxxxxx.

Xxxxxx is a code provided from Sprint when you activate the modem.