I'm taking a shot in the dark here. If you want to upgrade to two iPhone 8's, do you not already have two lines? Or are you trying to do the buy one get one free offer? If so, Verizon is not going to just give you and iPhone 8 to keep as a spare or sell it. The offer requires two lines eligible for upgrade or adding an additional line for the second phone. Read the fine print on the offer for details.
Such promotions would geared towards couples/families where one person has service with Verizon Wireless and someone else has service through another provider. If the second person agrees to switch to Verizon Wireless...and have their line added to the first person's account...then both users could upgrade their phones to...in this case...iPhone 8s.
As Chris said, if Verizon Wireless is either giving a phone or tablet away, or, at a reduced price, the will be a service commitment involved. The old saying that there are no free lunches applies here.
It seems to require adding an extra line. We have three phones, three lines. I need to upgrade two of them, both of which are eligible. I do not need to add a fourth line. Is that more clear?
Sent from my iPhone
Verizon is offerring the promotion for the new device a long with adding a line of service to increase revenue to help offset the large discount amount given.
If you don't want to add another line the iPhone8 BOGO may not be the right offer for you, but you may still want to check out your plan and consider the math of the implications in case the promotion may still benefit you financially.
For example, if you happened to have 3 current lines on the Go Unlimited Plan, the base cost would increase by $15 monthly to add a fourth line. (or $360 over 24 months). Since that would qualify a customer for the free iPhone 8 BOGO deal, even when factoring in the cost for the 4th line there'd still be a savings of over $300 since the price paid for the 2 new phones would be $700 instead of $1400. Some do decide to take advantage of promotions like that even if additional lines are not needed to save money overall on new devices.