What does a Cisco Expressway-E do when it receives a SIP REGISTER message from a Jabber client for MRA phone service registration?
A. It performs a DNS lookup for the Expressway-C and establishes a new TCP connection to it before forwarding the REGISTER message to the Expressway-C
B. It sends a 200 OK for the REGISTER back to the Jabber client if this client has previously been provisioned through the Expressway E and C pair
C. It sends a timestamped SERVICE message to the Expressway-C before forwarding the REGISTER message to the Expressway-C
D. It forwards the REGISTER message to the Expressway-C which then forwards it to the UCM for phone service registration
C
https://community.cisco.com/legacyfs/online/jabber-mra-call_flow-detailed.pdf
It is C. https://www.cisco.com/c/en/us/support/docs/unified-communications/expressway/212347-mra-phone-services-failing-due-to-source.pdf
c
C