swap to iPhone 8 - sim card & IMEI issues

[splucked]

sorry about that.  cat+keyboard=chaos

I'm currently using a 6 yr old Galaxy S4. It has a lot of issues and I'm dying to get rid of it.  My brother just gave me an old iPhone 8 and said it's unlocked.

First problem
My GS4. It has a micro sim. The iPhone takes a nano so I can't switch sims.  Do I need to buy a Boost sim for the iPhone 8 or can I get just any sim card?

Second Problem
The Boostmobile website will not accept the iPhone serial, IMEI or IMED. The resulting error msg is

db_no_data_found_exception-Client.701:089233818509897232 is not found in NMS

Data not found

I'm lost and could really use some help. 

[splucked]

UPDATE

It's now letting past the IMEI fields. but it's telling me that the SIM ICCID doesn't match the iPhone's ICCID.  

[melissac · Accepted solution]

Hi, Splucked. Did you enter the phone ID on the website to get a compatible SIM card? 

[splucked]

Hi Melissa,

Initially, I didn't have the purchase option. It fed me a screen explaining that my iPhone might be locked ... etc.

Tried again a  few minutes ago and got to where I needed to be.  SIM has been ordered so I'm all set for now.  

[melissac]

That’s so good to hear! If you have any other question or concern, just let us know.

[splucked]

Hi Melissa,

Just wanted to follow up.

Received new SIM today. Popped it in the iPhone, logged into my Boost acct & swapped devices in seconds. 

Don't think I would have found the right SIM without your help. 

Can't thank you enough.