I purchased my Droid Razr at the Bloomington, IN Sams Club a couple of months ago when they were first released. The counter person tried 3 sim cards while on the phone with tech support before she found one that worked..
A 3 foot drop to my basement floor resulted in a shattered 'gator glass' and necessitated a replacement which was handled promptly and professionally by Asurion. After several attempts, the supplied sim card would not work. I finally installed the card from my shattered phone which has worked fine until today.