[EXTERNAL] Re: Wifi Calling Firewall Holes to Punch

Fri Jul 17 21:39:45 UTC 2020

Jason/Josh:

Thanks for the input. The issue isn't NAT (we're not NATing). The issue is without NAT, the Wifi Calling feature apparently chooses to initiate inbound from the carrier to the client. When NAT'd, the client recognizes the NAT and initiates on its own. Or at least that what it appears. I calls 'em like I sees 'em. Whale biologist.

If anybody has AT&T, TMo and Sprint (because I suppose we need to hold on to them as separate objects until the merger is complete) it'd be much appreciated. AT&T only lists FQDN's here: https://www.att.com/support/article/wireless/KM1114459/ (which the Palo should [SHOULD] understand) but...paranoia I guess. Others have listed TMo as 208.54.0.0/17 and 66.94.0.0/19 as recently as 2018, and Sprint has exactly nothing.

And as I type this, someone chimed in offlist seconding 280.54.0.0/17 for TMo, so I'll add that to my list.

Thanks again everyone?!

John C. Lyden
Manager of Network Infrastructure, Infrastructure Services
Division of Information Resources & Technology

Rowan University
201 Mullica Hill Road, Glassboro, NJ 08028
rowan.edu/irt<http://rowan.edu/irt>

________________________________
From: Jason Alderfer <alderfjh at emu.edu>
Sent: Friday, July 17, 2020 5:00 PM
To: Lyden, John C
Cc: nanog at nanog.org
Subject: [EXTERNAL] Re: Wifi Calling Firewall Holes to Punch

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<mailto: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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