Wi-Fi Calling in a corporate environment

[chuckchurch]

Hey all,

 

   Question if anyone knows about cell phone wi-fi calling in
US.  Googling isn't finding what I'm looking for.  We have a corporate site
in US where users have BYOD capability, and use their phones with wi-fi
calling enabled.  Site uses a single NAT address (IPv4) for BYOD access.
Recently the site reported wi-fi calling had stopped working for all user
phones, Apple and Android, all about the same time.  The guest network did
have some bandwidth limitation applied and they had overuse.  That was since
resolved, we upped the bandwidth.  But the phones all still avoided wi-fi
calling.  It's a manufacturing site with known cell signal issues, so most
users had no signal via carrier.  I did not get a packet capture yet to see
what could be going on, we're 99% sure we're not blocking traffic.  I'm
wondering if the phones have an algorithm to test wi-fi signal, and perhaps
the carriers will blacklist public IPs with known wi-fi calling issues to
avoid cases where an emergency call can't be made because of intermittent
bad performance?  It seems odd that even when no bandwidth issues exist,
it's not attempted.

 

Thoughts?

 

Thanks,

 

Chuck Church

RE: Wi-Fi Calling in a corporate environment

[chuckchurch]

Thanks all.  Oddly enough, it seems that the entire site’s userbase suddenly 
started working.  From what I understand no action was taken to fix anything.  
So unless a dynamic PaloAlto update broke it and then unbroke it later, I’m not 
sure what was going on.  I’ll debug a bit to know what a working baseline looks 
like, since I’m not sure.

 

Thanks again,  

 

Chuck

 

From: Tom Beecher  
Sent: Friday, August 2, 2024 2:03 PM
To: chuckchu...@gmail.com
Cc: nanog@nanog.org
Subject: Re: Wi-Fi Calling in a corporate environment

 

My understanding has been that generally, if the cellular network signal was 
above a certain threshold, phones won't even attempt to use wifi calling. Some 
carriers used to let you flip a switch to force the phone to prefer wifi over 
cellular, but some have removed that. ( Verizon for example. )

 

In my experience some years ago in a similar environment, that cellular 
threshold to switch was set so low that it was useless. I could be standing in 
a spot with barely tickling the bottom bar, and nothing. If I flipped to 
airplane mode, was able to wifi call instantly. 

 

On Fri, Aug 2, 2024 at 11:11 AM mailto:chuckchu...@gmail.com> > wrote:

Hey all,

 

   Question if anyone knows about cell phone wi-fi calling in US.  
Googling isn’t finding what I’m looking for.  We have a corporate site in US 
where users have BYOD capability, and use their phones with wi-fi calling 
enabled.  Site uses a single NAT address (IPv4) for BYOD access.  Recently the 
site reported wi-fi calling had stopped working for all user phones, Apple and 
Android, all about the same time.  The guest network did have some bandwidth 
limitation applied and they had overuse.  That was since resolved, we upped the 
bandwidth.  But the phones all still avoided wi-fi calling.  It’s a 
manufacturing site with known cell signal issues, so most users had no signal 
via carrier.  I did not get a packet capture yet to see what could be going on, 
we’re 99% sure we’re not blocking traffic.  I’m wondering if the phones have an 
algorithm to test wi-fi signal, and perhaps the carriers will blacklist public 
IPs with known wi-fi calling issues to avoid cases where an emergency call 
can’t be made because of intermittent bad performance?  It seems odd that even 
when no bandwidth issues exist, it’s not attempted.

 

Thoughts?

 

Thanks,

 

Chuck Church