Depending on your carrier, SIMs weren't really used unless you were with AT&T or T-Mobile. The subsidized phone system here made switching out SIMs between pho

Depending on your carrier, SIMs weren't really used unless you were with AT&T or T-Mobile. The subsidized phone system here made switching out SIMs between phones kinda pointless so fewer people knew about them. Now, with LTE, that's changing a bit.