Like the title says, I have a Verizon iPhone with a grandfathered unlimited plan, is there anyway to activate a 4G LTE sim to use it in the Verizon iPad, with the unlimited data plan?
Of course while doing this one would not be able to receive calls.... I know that if you have an Android Lte the switching works with a tablet or mifi...
I did this exactly what you want to do.
Call Verizon and tell them you are going to switch to a 4g phone that requires a microsim. They tell you that you can go to the store but they'll charge you $25 if you do so ask them to send you one which will be free and 2nd day shipped to you. Once you receive it call the 800 number provided in the paperwork and tell the rep you are still choosing your phone but you want to activate the microsim without the phone, he/she will ask for the long 89 number on the card the microsim is attached too and will work so if get a person who says that won't work don't believe them hang up and call again. Afterwards be asked to be transferred to a sales rep as you want to add a line of service, once you do so tell them you activated your sim and getting a new line for your current iPhone as its going to someone else and you are getting a new phone. WHEN YOU DO THIS MAKE SURE YOU CHANGE YOUR TEXT PLAN FOR THE UNLIMITED PLAN AS IT WONT DO ANY GOOD TO PAY FOR IT AND YOU CAN'T USE IT, MORE ON THIS LATER. They'll act confused as your old number isn't showing a phone but still active just ignore them blabbering itll work. You pay a activation fee but doesn't hurt to ask for a waiver of that fee, and a new line of service is $9.99 plus $30 for a 2GB plan. You'll get a new number of course and that's that. You'll have to wait a little while for activation I had to wait an hour but this was when the new iPad was released.
After all that turn off your iPad, insert the microsim, turn it on, go to settings/general/reset/subscribers sevices/ reprovision account. Afterwards it should work. It did take a bit to get it working it'll say LTE and so far it's unlimited.
Now the downside, when you go to verizonwireless.com it'll notice you are on a iPad and if you go to change anything on your plan it'll say you need to upgrade your device which means you can't change anything like I said make sure you got your text plan set, I didn't now I'm paying $5 for almost nothing.
Other than that works great, loving my unlimited iPad LTE. Sure I'm paying the same as a 3GB equivalent plan but I'd rather have unlimited as LTE is broadband speeds and 3Gb is a nights worth of Netflix and web surfing. So far i've used 1GB already and I personally don't think i've used it much.
Enjoy! Msg me if you have any questions.