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HDX 6000 - can perform call from one end - but not the other way around

Occasional Contributor

HDX 6000 - can perform call from one end - but not the other way around



We've setup several HDX 6000 systems - with no problems, runs smooth :)


But here at our office we are trying to set up two HDX 6000, on different networks. 


Now we ran into a problem. We are able to call from one system, and the call runs smooth through to the other. But when we're trying the other way around, the call dosen't go through!

Furthermore, we experience now and then it drops the picture and sound to the far end!


The router in the end causing troble is a Linksys/Cisco E2000.


Ports openend in both routers (the second router is an Cisco ASA 5505)

1720 UDP

60000-60007 UDP

60000-60001 TCP


Any help would be much appreciated! :)


Message 1 of 3
Polycom Employee

Re: HDX 6000 - can perform call from one end - but not the other way around

A firewall will do what it was designed to to, keep out unwanted traffic. It must be configured to allow video traffic inbound.

Port forwarding must be properly setup for the correct port numbers found in the firewall section of the HDX Admin Tools

Nat must also be set up properly.  There must be a dedicated one to one Public NAT address.


The HDX Admin Guide explains the various settings


I have attached a document we have outlining the config for the ASA.


Also below is a brief explanation of NAT.


Here’s how I explain the function:


If the NAT is 323 compatible is checked, the unit is putting the ‘real’ (internal) IP address at both layer 3 and layer 7 of the packet.


If it is unchecked, the unit puts the ‘real’ IP address in L3 and the WAN IP in L7 of the packet.


NAT is compatible is extremely close, in real-world function, to having no NAT settings at all. When it is checked, the unit is depending on the firewall to intercept the packets & do the L3 NAT (change internal IP to external IP/vice-versa), as well as open the payload of the packet, determine if there is anything ‘to do’ (such as determine if it is an H245 packet and alter the IP address/port numbers contained therein) & do whatever is necessary.

When not checked, the codec has the simple thought process of: “the firewall here is dumb, so I have to put the WAN IP in the payload part so this call will work”


The layer 3 part of the packet, regardless of the NAT settings, is the same as it would not work otherwise.

Sr. Product Support Technician
Occasional Contributor

Re: HDX 6000 - can perform call from one end - but not the other way around

Thanks for the fast reply. 


However, we found that the Linksys E2000 was causing the problems. Calling between ASA 5505 boxes works just great!


i've saved the .pdf attached for later use :) THANKS ALOT!



Message 3 of 3