One way audio until hold

Hi everybody!
This is my first post here, so if I’m doing something wrong, please let me know :smile:

I’m experiencing some strange one-way audio issues on a new Kamailio/Asterisk platform we’re building. I’m not sure if it’s a local issue with our network here - it seems like it is, but it’s strange because the network here is extremely simple (just a TWC connection with a standard router - no ALG or other stuff enabled).

When dialing to a phone on our network, there’s only one way audio. The caller hears audio, but the callee doesn’t - until the callee puts the call on hold and retrieves it again, then it suddenly works.

We can’t really find anything strange in the logs - all RTP packages are being sent correctly, and when you put them on hold, they stop being sent… Retrieving the call from hold, starts sending them the exact same way, but now the callee suddenly hears them.

With that said, the interesting part is, that we don’t have this problem when connecting with Bria over our cell phones, and I also tried with a Grandstream wifi phone using my cellphone’s shared internet - that worked fine too.

We have turned off ALG in our router, and there’s nothing specific there, that should mess things up.