Troubleshooting SIP IP Telephony Issues: Possible Solutions for Intermittent Voice Problems
Question
Cisco SIP IP telephony is implemented on two floors of your company.
Afterward, users report intermittent voice issues in calls established between floors.
All calls are established, and sometimes they work well, but sometimes there is one-way audio or no audio.
You determine that there is a firewall between the floors, and the administrator reports that it is allowing SIP signaling and UDP ports from 20000 to 22000 bidirectionally.
What are two possible solutions? (Choose two.)
Answers
Explanations
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A. B. C. D. E.AC.
https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/port/9_1_1/CUCM_BK_T2CA6EDE_00_tcp-port-usage-guide-91/The intermittent voice issues reported by users in calls established between floors of a company where Cisco SIP IP telephony is implemented could be due to the firewall that is present between the floors. The administrator reports that the firewall is allowing SIP signaling and UDP ports from 20000 to 22000 bidirectionally. To resolve the issue, two possible solutions are:
A. Go to the SIP profile assigned to these IP phones in Cisco Unified CM and change the range of media ports to 16384-32767.
This solution involves changing the range of media ports for the SIP profile assigned to the IP phones in Cisco Unified Communications Manager. By default, the range of media ports for SIP is 20000-30000. However, the firewall is only allowing UDP ports from 20000-22000, which could explain the intermittent voice issues. Changing the range of media ports to 16384-32767 would ensure that the media traffic is using ports that are allowed by the firewall.
D. Go to the SIP profile assigned to these IP phones in Cisco Unified CM and change the range of media ports to 20000-22000.
This solution involves changing the range of media ports for the SIP profile assigned to the IP phones in Cisco Unified Communications Manager to match the range of ports allowed by the firewall. However, this may not be the optimal solution as it restricts the available media ports to a narrower range.
B. Ask the firewall administrator to change the ports to TCP.
This solution involves changing the transport protocol used by the SIP traffic from UDP to TCP. This would require coordination with the firewall administrator to allow TCP traffic and may involve changes to the firewall configuration. However, TCP is generally considered a more reliable transport protocol for voice traffic.
C. Ask the firewall administrator to change the range of UDP ports to 16384-32767.
This solution involves asking the firewall administrator to expand the range of UDP ports allowed to include the default range of media ports used by SIP, which is 20000-30000. This would ensure that all media traffic is allowed through the firewall, but it may not be possible if the administrator is unable or unwilling to make the change.
E. Go to System Parameters in Cisco Unified Communications Manager and change the range of media ports to 20000-22000.
This solution involves changing the system-wide media port range in Cisco Unified Communications Manager to match the range of ports allowed by the firewall. However, this may not be the optimal solution as it restricts the available media ports to a narrower range.
In summary, the two possible solutions are changing the range of media ports for the SIP profile assigned to the IP phones to either match the range of ports allowed by the firewall or to a range of ports that are allowed by the firewall. Alternatively, changing the transport protocol used by the SIP traffic from UDP to TCP or expanding the range of UDP ports allowed by the firewall to include the default range of media ports used by SIP may also resolve the issue.
