For those on T-Mobile, the Micro-SIM is $0.99 online + tax w/ free shipping when you order a pre-paid activation kit. Use that SIM kit and update the registration online using my.t-mobile.com, or activate the new SIM as-is if you're going the prepaid route. The same card in a retail store will run $9.99+tax.
Sim Card Activation Kit For Prepaid Phone or Unlocked iPhone | T-Mobil
I ordered mine today to ensure the new SIM would be in-hand when the N4 arrives.
I think its a mini.Go into a provider branch and they should replace your card for free or cut it for you.
the term is Micro. the other smaller one is nano.
@OP N4 has micro