windows ce 还是Windows mobile呀
如果是windows mobile监听注册表项
// PhoneCallCalling
// Gets a value indicating whether the phone is currently attempting to connect an outgoing call.
#define SN_PHONECALLCALLING_ROOT HKEY_LOCAL_MACHINE
#define SN_PHONECALLCALLING_PATH TEXT("System\\State\\Phone")
#define SN_PHONECALLCALLING_VALUE TEXT("Status")
#define SN_PHONECALLCALLING_BITMASK 0x20000