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IP Address Requirements for Remote Phone Proxy

Hey guys and gals, I've got a customer requesting that Phone Proxy be configured on their ASA and they're asking me exactly what is required for said feature.  I referred to this Phone Proxy configuration guide for ASA 8.2(x) and it seems that the main requirements are the Phone Proxy feature license for the ASA as well as some number of public IP addresses for Media Termination Address and TFTP Server(s).  The configuration guide clearly dictates that a unique public IP is required for the Media Termination Address; however, the example scenario also has another public IP allocated to a static NAT for the TFTP server (presumably the publisher) but doesn't explicitly say whether a public IP is required or if a NAT overload on the existing interface is acceptable.

What's the best way to configure the addressing here?  Can you get buy with only one new external iP?

I cross-checked the requirements with and he seemed to agree that two unique public IPs are required for phone proxy.  Can someone please verify the public IP address requirements for phone proxy?



Cisco Employee

IP Address Requirements for Remote Phone Proxy

Hi Phil,

You'll need two public ip to make this work, one IP assigned to the ASA outside interface and another one to map the CUCM+TFTP. The MTA must be a unused public IP plus there must be a way for the  outside IP phones to router to the CUCM and TFTP server.

You can refer to this document as well:



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Regards, Tere. If you find this post helpful, please rate! :)
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