how to get the ESN of a Mobile Broadband using the mbnapi?

Please let me know if there is a better forum to ask my question.

I have created a VS 2010 C++ program to communicate in LAN, WWAN or WI-FI. The program runs under windows 7. In the previous release of this program, we were using QCWWAN2K.dll to communicate in WWAN but now the customer requested to use the Mobile Broadband API of windows 7 (mbnapi.h). Everything is working fine except the fact that I can't get the ESN number of the mobile broadband adapter. The function I am using is IMbnInterface::GetInterfaceCapability. This function should return the IMEI for GSM devices and ESN/MEID for CDMA devices. In my case, it's a CDMA device but it always return the MEID. I really need to get the ESN.

Is anyone know how to do it?

Thanks in advance.