Jabber to Jabber voice calls fails when connected to same VPN firewall using AnyConnect

[ENZO CAPPUCCITTI]

                   Remote Jabber users connect to corporate network via AnyConnect VPN client. We tried PC's iPads and iPhones devices. The can IM with each other, they can see their presence status as well. When they try a voice call, the calls are processed and rings the called party but there is no audio.The Jabber client can call any other devices on corporate network without issue.

We had one user VPN through another corporate firewall and the call goes through and they have full 2-way audio.

Did some testing and found the 2 devices could not ping each other. Checked Firewall config and added same-security-traffic permit intra-interface. Users were able to ping each others VPN address, but still no voice audio streams during a voice call.

[jferris1979]

Hi Enzo,

It sounds like your RTP ports are being blocked by the firewall.  Once the call is connected the RTP audio stream uses UDP ports in the range 16384-32767. The first thing I would check is that this port range is open in the firewall. 

HTH,

James

[JMcNichol]

I encountered the same issue and conducted a thorough verification of NAT, ACL, and ACP configurations, as well as inter-VPN communication. Additionally, I disabled SIP and Skinny inspection. A packet capture (PCAP) analysis revealed no significant packet loss compared to onsite users. To optimize traffic flow, I implemented a FastPath rule on our Firepower Threat Defense (FTD) appliance to facilitate communication between our VPN pool and voice gateways. This fixed out issue!