So I am in Brazil with my droid charge and I want to make some local calls. I bought a TIMChip GSM card and replaced my Droid Charge's sim card and restarted. I get an "unknown SIM card" warning and i tried to activate it by making a call. After tinkering around the options I was able to set the network to CDMA mode and make the call but i get cut off immediately after the call is "being made". I see that the TIM Chip is GSM and it seems CDMA phones dont use SIM cards but how come there is a slot for it in the back of the droid charge housing my LTE chip? Or is it just a coincidence the shape is the same? As a followup, what are my options for being able to make local calls without internet help? thanks!