Hey folks! I'm dealing with a frustrating issue at my mid-sized company, where we have about 550 users across three states and over 60 locations, all using the same cloud VoIP platform. Lately, we've been experiencing random one-way audio calls. The only temporary fix has been to reboot the phones. Our vendor, Vonage, is pointing fingers at the network, but when we checked with packet captures, everything looks fine on our end. The problem is that it's hard to catch these issues live since users don't always report them while they're happening. Any ideas on how to solve this or where to start looking? Has anyone else faced similar VoIP problems? We're using Yealink phones, by the way. Thanks!
5 Answers
It might be a firewall issue that's messing with your SIP traffic. Since you mentioned using Sophos, I recommend checking their support resources or reaching out to them directly to get some guidance on how to fix your one-way audio problem.
As others mentioned, SIP ALG can cause one-way audio problems since it alters SIP packets, which isn't ideal. You'll want to investigate your firewalls or routers—especially if you’re using SD-WAN, everything might be controlled from there. It might help to track when the problems occur and compare that with logs from your network devices. You could also ask your SD-WAN vendor how to turn off SIP ALG or any potential traffic modifications. If you have multiple ISPs, look into making your sessions sticky, so VoIP traffic consistently follows the same path unless there's an issue. This might take some coordination with your SD-WAN setup.
We’ve seen the same problem with Vonage, but using Polycom devices. Our setup routes the VoIP traffic directly to the internet too. So, I definitely understand being skeptical about Vonage's claims.
I'm also using Vonage with multiple locations and haven't had issues – except for their rare outages. Have you checked how your VoIP traffic is routed? Ideally, calls should go directly through the local ISP instead of your main data center for better response. Also, are you running any traffic inspections like dpissl? VoIP traffic should be exempt from those to avoid hiccups. If you have SD-WAN, make sure it's configured not to interfere with VoIP.
I don’t have dpissl, but we do use SD-WAN.
Have you checked if SIP ALG is disabled on your firewalls? That can often cause one-way audio issues.
I think I’ve disabled it, but I’ll double-check.
Thanks for all the detailed information. Really appreciate it!