For Inbound calls user not able to hear voice agent

Nilkanth
Thu, 09 Apr 2026 11:02:01 +0000
Telephony

Hello guys, I am facing issue where voice agent’s voice is not reachable to SBC, while the user’s voice is able to received by voice agent. The problem is recently LiveKit changed their PCAP mechanism and its showing IP’s that are not of SBC and I am not able to properly debug the exact issue. Here’s what I have tried

1. Checked if firewall has whitelisted the IPs for india region. Configuring firewalls | LiveKit Documentation

2. The call is able to connect but voice agent’s media is not coming.

3. I tried to keep my SIP Gateway server in between and tried to connect and it worked but the it increases latency.

4. I checked SBC PCAP and they are not receiving any RTP packets

5. I checked Livekit PCAP and its sending packets to local IP and I am not sure if its actully sending to local or just PCAP is shown local IP in destination.

6. It is occuring for inbound calls i.e call is initiated by the customer and SBC transfers it to Livekit. For outbound calls its working perfectly fine and medias are also being exchanged properly.

NOTE: This is the second telephony provider that we are facing this issue with.

Sharing you the PCAP of LiveKit and TekInfo (Telephony provider) and Transcript screenshot. Both PCAPs are for different test calls.

tekinfo_side_pcap.pcap (210.7 KB)

capture_livekit.pcap (57.2 KB)

5 posts - 2 participants