Refer to the exhibit.
Which out-of-dialog SIP OPTIONS ping response put dial-peer tag 1111 into its current operational
state?
A.
501 Not Implemented
B.
504 Server Time-out
C.
408 Request Timeout
D.
486 Busy Here
E.
503 Service Unavailable
Explanation:
SIP 503 Service Unavailable is commonly seen in a VoIP network when a SIP device (such as a SIP
server) is knowingly unable to process a call. Typically when this happens the endpoint that
originated the Invite will try the next available host it receives in the SIP Contact header.