5550 One way audio sometimes

[martyn]

Got a bit of a strange one where a 5550 console is at a remote site, and if you ring it from another site you get one way audio. If the user of the console rings you from the remote site, then the audio is two ways and everything is fine.
There are a stack of other phones in the same subnet as the 5550 and they all work no matter which way the voice traffic.
The 5550 can be dialed, and can dial within its own site fine (ie same subnet).
Both the phones and the 5550 have the same default gateway, subnet mask, etc.
The keypad can be pinged from anywhere else in the network with no issues.
There are no firewalls, ACL's, etc in between, just straight routing.

Scratching the head, as obviously the RTP (and signalling for that matter) stream works as if the console calls anyone else there isn't an issue, just an issue when someone else calls it.

Any other suggestions for where else things could be a miss? I'm starting to leave marks on my head from scratching it too much.

[wiseguy]

A network capture should let you know who is sending RTP and where to.

[ralph]

I agree with Wiseguy.  You'll need to do a packet cap at the console.

Ralph

[martyn]

Yeah that was my next step, but just thought i'd see if there were any other ideas before going that far!

[LoopyLou]

Agree with you it is strange.

When you call the 5550 which direction is the one way audio? They only hear you or you only hear them? Just want to confirm that the keypad is on the same subnet as the phones at the remote site. Seen lots of deployments where it is on the data VLAN and is routed to the VLAN to connect to the 3300 since the console doesn't understand LLDP. You have the Static IP address entry for the console key pad in the 5550?

You say the 5500 and the phones have all the same setting but is that only at the remote end. What are the settings at the prime (non-remote ) end

[martyn]

We are in the process of replacing the key pad, as apparently it was a faulty one that was put in to replace a DOA one! Handy...

[martyn]

Turns out that whilst the keypad needed to be replaced for another fault, it didn't fix this problem.
The problem is actually an MCD 6 issue relating to Direct IP trunks, and compression zones, that will be fixed in the next release apparently.