I thought that was the main difference between GSM and CDMA (aside from the Tech used in the transition of signal)
that GSM phones has SIM cards and CDMA phones were hard wired.

that why I like GSM. Got a new phone? pop in your SIM card and you're ready to go. traveling abroad? pop in a local pre paid SIM card and you're not screwed by roaming charges... that is if your GSM phone is unlocked.

When I left the states 5 years ago and took my little Ericsson world phone with me (T-28 if I remember correctly) I had to get some blood from a stone but T-mobile did give me the unlocking sequence eventually.
Since then all phones I buy out here are unlocked by default.