Sprint's Spark Phones Don't Support Simultaneous Voice/Data
Top message: LOLZ by Versed
Replying to: special by Zpike
You do know that the Note 3 only does sim voice/LTE, not voice/3G, so it's inherent in the device design. Nothing Sprint "did" or "didn't do".
You'll find the same experience on Verizon devices as well.