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Calling from one endpoint to another

Hello i hope you can help me with the next problem :

I have one endpoint E20 with one ip 213.149.... and i want to call an ip behind a router with inner ip .The VCS and the MCU are behind the same router with ips and .When i try calling from to 213.149.... it calls but when i try calling from 213.148...... to there is no result. I have opened the ports 5060 ,5061 and 1719 on the router. I hope that i have explained it correctly. Thanks for the help you are great!

Dharmesh Nandoria
Cisco Employee


Issue you are facing is expected beheviour , You can not call private IP 192.168.x.x from public IP . Private IP are not routable from internet .

Kind regards,


Hello Dharmesh i was thinking that if i try to dial for example with privet ip 192.168.x.x from with ip 213.159.x.x it will connect to proxy1 with the public ip of 192.168.x.x and through some ports will find the uri in the vcs and everybody are happy ...


To achieve that you will need a VCS-E in addition to the VCS-C (or a VCS-E starter pack instead of the VCS-C) - and have the appropriate DNS SRV records in place. Strongly recommend taking a look at:


Please rate replies and mark question(s) "answered" if applicable.

Please rate replies and mark question(s) as "answered" if applicable.

This is how it looks like When i try calling from It calls without video but with audio,and when i try calling from cannot connect call. Thanks again

Hi Svetoslav,

I guess you are dialing from e20 ( to e20 ( using it's IP not URI, correct?

Now if you are dialing from e20 ( to e20 ( then you have to use its URI as registered on the VCS expressway. For that to work make sure the DNS SRV records are in place so that resolves to the VCS expressway public IP.

In other words the sip request to call, say, should be resolved by he public DNS sevrers and hit the VCS public IP address.

What is the router thst is doing NAT? IOS and model?


Hello Andrey

i'm dialing the uri of the e20( on the phone System information there is : Sip Status: Registered. It calls the phone but  the e20('t send video and audio to e20( The router is just for testing TP LINK  TL-WR740N. The other router that will be on it's place is Cisco 2900 series.

I think i can explain it better in bulgarian it will be great if you can give me skype and help me out with this if you have time. Thanks for the fast replay and regards!

Alok Jaiswal
Cisco Employee

Hi Svetoslav Simeonov,

It could be a issue with the firewall port openings. Please ensure that you have proper ports opened.

Although for this kind of solution vcs-exp is required or you put vcs-ctrl on the public ip.



Thanks for the replay! I have opened ports :

95061192.168.1.248ALLEnabledModify Delete
101720192.168.1.248ALLEnabledModify Delete


Modify Delete


Modify Delete


Modify Delete


Modify Delete


Modify Delete


Modify Delete



Modify Delete


Modify Delete

I don't have any vcs expressway ...  Thanks again.

Hi Svetoslav,

its not very clear from which direction to which direction you have opened the ports.

when you make a call frm E-20 reg to VCS-cntrl the call will be dialed out thorugh VCS control and will be sent out as H.323 call to remote endpoint.

I am not sure but when you make  a call from E20 what is your source protocol sip or H.323? in case if you do an interworking then VCS shall take the media.



First i want to thank you all! I'm very happy that there are nice people who want to help others.Thanks friends

Hi Alok,

i'm not sure what am i doing with the ports i have opened all port to the VCS. When the call is dialed out through VCS which port should be opened to which ip The source protocol is SIP. When the call is between two endpoints E20 with ips 192.168.1.x and 192.168.1.x there is no problem with audio and video when i call the MCU from the endpoint(192.168.1.x)there is no problem joining conferences

Basically ports range above 1024+  can be used for signaling & media and this port range varies with different types of endpoints. in the current scenario you can pull the diagnostic logs from the VCS and see how the call is going to remote endpoint.

Basically when you have this kind of scenario the expressway is required where in you can define the NAT address so that the headers for call signaling can be modified accordingly. Not all firewall are capable of doing a deep packet inspection and modifiy this headers. I believe the router you are using for the NATing support packet inspection but upto which level not sure.

As a workaround you can put the VCS-control on the public ip rather than using the NAT.


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