Just thought I'd pass along an update.
The 'engineering ticket' was successful. They de-coupled my new iPhone 7 Plus from the Verizon number used during purchase, and setup a way to bypass the activation server by putting all zeros in for the zip code and all zeros for the last 4 digits of the Verizon account holder's SSN.
After getting past the activation screen all seems well and I was able to restore as a backup of my previous phone. WiFi calling had to be re-enabled but activated in about a minute and works flawlessly. VoLTE also works seamlessly with no issues.
This upgrade was from an AT&T iPhone 6 Plus, so the SIM cards are fully compatible at least 2 generations back.
I have 2 more phones coming this way, so unfortunately it looks like it will take an engineering ticket and 4 hours each time to bypass the Verizon activation. But at least there is a success path.
Thanks for this. I just went thru an interesting, similar scenario so want to share my thoughts.
I went thru this same process having issues, getting past the Verizon Billing Zip/last 4 ss #, in the store. I had a VZ rep assisting me, and Apple Genius, and no one was able to figure it out. I knew I was inputting the correct information, given I just entered the same info to order the phone a week ago, however I just couldn't get past the Verizon authentication to continue activating my phone.
Left the store saying I'd leave and try to figure it out myself. Once I returned home, I got the idea to try a different zip code. While my plan's billing zip is in another city entirely , I decided to try the zip code where the phone was shipped instead (Dallas). Upon entering the shipping zip code and last 4 of the ss, I was able to get thru. Some word of advice for those who are in a similar scenario. It appears the authentication may be based on shipping zip code rather than billing zip code as it says in the iPhone UI.
Also, another interesting note: during my time in the store they were also telling me about this new Apple device association for which the device is ordered. I can confirm Apple themselves are creating associations with the phone numbers/devices, at least for Verizon iPhone 7's. . As you said in a post above, even a DFU restore will not bypass this association. So you're forced to be aware of the info (the goal is to stop scalpers). However, upon activating service on the new phone with the SIM Card that was included in the new phone, it did NOT deactivate my old phone. So, I don't think you really had to go thru the steps to avoid having your buddy's line disconnected-- though it was wise that you did and considered that. However, in my experience, I believe all you have to do is bypass the authentication-- the actual device activation is based on whatever SIM card you used. The included SIM card for the iPhone 7 is NOT needed.
Edit: Forgot to add-- don't know if this matters, but I did pick up the phone via an in store reservation versus ordering it online. Not sure if this would impact the flow of the activation process or not.