I'm getting the correct sim card sent to me. This is what I went through:
I just got my project fi phone today. I decided to stay with my current Sprint plan for a few more months. I have to tell you, this is a nightmare. I of course tried to just swap my nano sim card from my current Motorola Nexus 6 to the new Nexus 6p. The phone tried to activate the sim card automatically(no dice). Sim card locked!!! Please call Sprint. I then tried the online sprint webpage where you can activate new devices. No GO!!! Device not in database. Then I Initiated a chat with Sprint. They asked for IMEI number, serial and sim card number. NO go, I then tried another brand new Sprint Nano sim card I got from a sprint store this week. That wouldn't work either. So then I drove to a Sprint Store. I had the guy at the sprint store try for 2 hours, and 3 calls to corporate. Apparantly there is a special sim card required for the Nexus 6p. And will take 3-5 business days. No expedite option available. WTF Brand new phone, cannot use it with Sprint currently. That is my experience, hope yours is better.