What is the usual procedure taken if an unrecognized non-mandatory ISDN IE is received by a
network?
A.
Final handle the call
B.
Final handle the call if 2 such IE is received
C.
Ignore only if the IE received is not CSO, otherwise final handle the call
D.
Send a Facility msg to the user notifying the user of sending unknown lEs but don’t final handle
E.
Ignore the lEs