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Community Member

VT between firewalls

Hi, which protocols and ports must be open in an firewall for using Cisco VT? We are using Cisco 7940 phones and Cisco VT version


Re: VT between firewalls

Cisco VT Advantage communicates with the IP Phone using the CAST protocol (4224/tcp), so this needs to be opened between the Voice VLAN and the Data VLAN (The IP Phone effectively acts as a Skinny proxy to CTVA, in order to establish the video RTP streams). The video streams themselves use 5445/udp, so this port must be opened between CVTA video endpoints on the Data VLAN.

By default, when a video call is negotiated, both audio and video packets are marked with DSCP AF41 (not EF in the case of an audio-only call). This should be reflected in your QoS policies.

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Community Member

Re: VT between firewalls

Hi, I have attached a gif file. We have an headquarter and several departments. Between these we have firewalls. The CCM is placed at the headquarter. An employee at the headquarter and an employee at the department are using Cisco VT. Is it enough to open for 5445/udp in the firewalls?

Best regards paal


Re: VT between firewalls

If there are no ACLs between Voice and Data VLANs at each site, then opening 5445/udp (inbound and outbound) on the firewalls should suffice. Presumably, you have entries to permit voice RTP streams and Skinny control traffic between remote sites and headquarters? Opening 5445/udp should allow the video RTP streams to be established.

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