Wifi Calling Firewall Holes to Punch

Fri Jul 17 21:00:01 UTC 2020

In our university environment, wifi calling works just fine over NAT and
we have not made any inbound port exceptions in the firewall for it.  The
critical piece for (non-enterprise) VoIP traffic is that your firewall must
not try to function as a SIP ALG, but I'm not sure that's directly relevant
to wifi calling for the major carriers.

Jason Alderfer
Director of Technology SystemsEastern Mennonite University

On Fri, Jul 17, 2020 at 12:40 PM Lyden, John C <lyden at rowan.edu> wrote:

> Hey gang.
>
>
>
> We’re setting up a unified wireless network for the students here, and to
> get around the issues with Nintendo and NAT we devoted a large chunk of
> public IP space to them.
>
>
>
> We’re aware that this is causing issues with wifi calling on Verizon, TMo
> etc because it appears they initiate the SIP session inbound.
>
>
>
> Does anybody have a handy list of IP blocks and ports? T-Mobile had a
> decent page but other providers just said “open up 4500 and 500” and our
> ISO guys don’t like that.
>
>
>
> Thanks if someone can help.
>
>
>
> John C. Lyden
>
> Manager of Network Infrastructure, Infrastructure Services
>
> Division of Information Resources & Technology, Rowan University
>
>
>
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