SIM Not Valid

Dear All,

Recently I received an iPhone 6+ as a replacement for my broken phone through AppleCare.

To my surprise, my existing SIM (carrier Mobilicity) is not getting activated on new phone and throwing me an error "SIM Not Valid".

I assume that the new phone should be unlocked and accept any supported carrier (Just like my old broken phone which I purchased from store).

My question is:

1. Is it because my new phone is locked?

2. Is there a possibility that I received used/refurbished phone from Apple instead of brand new phone?

Thanks,

Umesh