static extern void InitManagedSession(IntPtr sessionPtr, DtmfCallback dtmfDelegate, CdeclAction hangupDelegate);
static extern void InitManagedSession(IntPtr sessionPtr, DtmfCallback dtmfDelegate, CdeclAction hangupDelegate);
static extern void InitManagedSession(IntPtr sessionPtr, DtmfCallback dtmfDelegate, CdeclAction hangupDelegate);
static extern void InitManagedSession(IntPtr sessionPtr, DtmfCallback dtmfDelegate, CdeclAction hangupDelegate);