Swap Phones on Two Accounts?

I have two activated phones on two different accounts that I’d like to swap. Can you suggest a way how to this?

If you are the account holder of the two numbers, you’ll just have to phone a cs or visit a store with VZW store with the two handsets.

You can also do this through online ESN changer, but you’ll need a third unused phone as well as an online account for both accounts.