Which SIP message header is used to tunnel QSIG messages across the SIP network when the
OGW receives a call bound for the TGW?
A.
Content-TypE.application/sdp
B.
Content-TypE.application/qsig
C.
Content-TypE.message/ISUP
D.
Content-TypE.message/external-body
E.
Content-TypE.application/x-q931