TW No Audio - Error : loss of rx stream from IS for 5001ms

[warlockcode]

Hi

I have this issue with my Teleworker phones having no audio at all when you call through the public SIP trunk to an external device.
However, there is audio both ways if you call from a TW set to another TW set, or from an internal ext to a TW set. There is also audio both ways when you call from internal ext to the public SIP trunk. Issue only with TW to SIP.

My setup consists of a MiCollab server, MiVoice Business and MiBoarder Gateway. Both my MiVOice and Micollab sits in the same LAN, while MBG sitting in the DMZ with basically all the ports in the Engineering guideline opened. I have both MBG in a cluster (MiCollab and vMBG).
I have standard UCCv3 user licenses which provides me with the TW licenses.

TNA says that all ports are fine (port 6800 appears to be closed - should this be opened), externally and internally.
No alarms on the controllers or Micollab, but I get "loss of rx stream from IS for 5XXXms" on my vMBG server.

All networks is added as trusted on all servers.
SIP is terminated directly to the MiVoice (MCD) and not via MBG as voice network sits within the Telco's MPLS network, however vMBG has open access to the LAN so it is able to see the SIP end.

I have seen this issue before but not really sure how it was resolved.
Not sure what is causing this, any help is appreciated.

Thanks.

[ralph]

My first guess is that it's not routing properly to the SIP gateway.
Remember that when a call is set up, the IP traffic then routes from device to device (In this case TW server to SIP server) and the 3300 drops out.   
If your firewall has all ports open between the TW server and SIP server then I'd suspect the issue is with IP routing.

Putty into the TW gateway and do a trace route to the SIP server to see what you get.   Note, if the problem is that the TW phone can't hear then the routing problem is most likely with the SIP router.

Ralph