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Community Member

Private IP Address

My internet service provider give us a private IP address on the outgoing serial interface.

How do I work around it so that my source IP address will be a valid IP address instead of using the default IP address of the outgoing interface.

At the router, I need to use extended ping command (i.e. by changing source ip address) in order to ping the addresses outside internet.

For your information, I try to setup voice over ip.

Any help will be appreciated.


Re: Private IP Address

Your source IP address will be the Telephony device. I guess maybe I don’t understand your setup.

Cisco Employee

Re: Private IP Address

Do you mean that you have voice ports on this router and you want to setup H.323 calls on the Internet side? If so -- Configure the ip address you want to use on a Loopback interface, and bind H.323 setups to it. For example:

interface Loopback0

 ip address

 h323-gateway voip bind srcaddr

Community Member

Re: Private IP Address

I am in the same boat. I have several customers who use products like linksys and netopia routers. They have a static IP address on the ISDN or T1 port but they use private address on the internal side. Most of these devices are router/hub combo's and are quite popular. The Call Managers sees the phone and they do register but they register with the private address. I tried opening a UDP port directed to the IP phone but I still get one way voice. The phone can send but not recieve. Any help out there?

Community Member

Re: Private IP Address

I forgot to mention that I already have the voip bind command set. So I don't think it's that.

Community Member

Re: Private IP Address

First of all, I would dump the non-Cisco routers…hehehehe, just kidding J

I do need clarification. Are you running NAT or PAT on your router? Is the ISP supplying you with a private IP address? If so, then their running NAT or PAT.

Perhaps you and the ISP are running NAT/PAT ?

Are you trying to link an IP phone across the Internet to a call manager on the other end?

If so, remember IP phones register and connect to the CCM via the Skinny protocol. Typically NAT needs to recognize the contents of the skinny packet. Selsius developed skinny, which is who Cisco acquired a few years back.


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