No prack on ringing

[slayerphil]

Hello

I'm looking into an issue at the moment that's stumping me a little. All calls are working fine other than a single destination, they have a PBX the other side, I'm not sure if this is relevant.

When I send calls to the destination everything seems fine and then I receive ringing back, shortly after another ringing is sent back to me about 4 times, until it fails with a 504 server timeout from the destination. It looks like I'm not sending a PRACK back, I am in all other good calls. It's just this single destination where it wont connect.

Any pointers/ideas where to look?

Thanks
Phil

 

[DigitalDaz]

So they are specifying Require 100rel in the response?

I guess from reading the docs I have seen, the low hanging fruit here may be to send it them over TCP, is that an option?

My understanding was that this is mainly fro ISDN type gateways etc.