During a business-to-business video call through the Cisco Expressway solution, the internal endpoint can call out to the remote endpoint on the Internet, but it does not receive audio or video. The remote endpoint receives both audio and video.
What is causing the issue?
A . The Cisco Expressway does not have a Rich Media Session license.
B . The firewall is blocking SIP signaling.
C . The Cisco Unified Communications Manager is not configured for business-to-business calling.
D . The firewall is blocking inbound RTP ports.
E . The Advanced Networking option is not installed on the Expressway Edge.
Answer: D