Is Sprint a CDMA or GSM network?

[Ubun2]

I looked online but I can't seem to find the answer to this question. I want to know because I know AT&T's GSM network can do calls and internet at the same time.
PLEASE state you source.
PLEASE state your source (online, friends, media, etc.)

 

[Keil T]

CDMA, so it cant do phone and web at the same time.