Verizon wifi calling limitations?

[xraydoc]

As a Verizon customer, the release of iOS 9.3 brings my first hands-on experience with wifi calling.

I noticed at home on wifi it says "VZW WIFI" as the carrier name in the top left corner as expected. Today, I'm at a Barnes & Noble bookstore on their free AT&T wifi. Though I have a working wifi signal (as evidenced by this post), the carrier name has not changed, so I'm presuming something is stopping the phone from switching to wifi for voice.

So, if anyone knows, what are the conditions that tell iOS that it can switch to wifi for voice versus LTE (or, god forbid, crappy Verizon 3G)??

 

[olepi]

Turn airplane mode on and then turn your wireless on. That usually forces it to wifi calling. Least that's what I do here at work to help with battery life.

 

[kch50428]

Near as I can tell, Verizon's wifi calling will stay on cellular until the cellular signal goes below two full dots/bars... or -100 or so if you have test mode enabled... and switches back to cellular when signal is something better than 2+ dots/bars signal - or somewhere in the -90s for those using test mode - I haven't been able to nail it down, but I believe there's some sort of background assessment of the quality of the wifi connection going on too...

 

[xraydoc]

Are there specific network ports that, if blocked, will disable wifi calling?
[doublepost=1458663847][/doublepost]

Near as I can tell, Verizon's wifi calling will stay on cellular until the cellular signal goes below two full dots/bars... or -100 or so if you have test mode enabled... and switches back to cellular when signal is something better than 2+ dots/bars signal - or somewhere in the -90s for those using test mode - I haven't been able to nail it down, but I believe there's some sort of background assessment of the quality of the wifi connection going on too...

I have good cell signal at my house, so I don't think that's it. When I first enabled it, the phone hopped right on to wifi.

 

[timeconsumer]

Are there specific network ports that, if blocked, will disable wifi calling?

UDP 500
UDP 4500

Source: https://support.apple.com/et-ee/HT202944

 

[xraydoc]

UDP 500
UDP 4500

Source: https://support.apple.com/et-ee/HT202944

Helpful. Thanks.

 

[C DM]

Near as I can tell, Verizon's wifi calling will stay on cellular until the cellular signal goes below two full dots/bars... or -100 or so if you have test mode enabled... and switches back to cellular when signal is something better than 2+ dots/bars signal - or somewhere in the -90s for those using test mode - I haven't been able to nail it down, but I believe there's some sort of background assessment of the quality of the wifi connection going on too...

Yup, generally that's how it is.