CDMA phones cannot talk and data at the same time - even SMS.
I believe GSM phones are the same. This applies only to when working from the cell towers. If you are also in WiFi then it is up to the phone.
Your sprint curve can not do that. What it can do is phone + sms. Data can not be transferred when a call is in progress. What it does it holds the incoming data until the channel is free (when the call is disconnected).
The only phones that can do this w/o wifi are 3g UMTS phones. This means the 3g for CDMA can not.
Right now, only BB that can do all is the Bold. (without wifi). With wifi, all phones have that capability.
In conclusion, you can only send and receive sms while on a phone call with cdma carriers, whether on 3g or not.
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