Got a call from 864-349-4000 today...
A search (as above) shows it comes from South Carolina.
For some reason, Synnex corporation uses this number for their A/R department to call account holders.
SYNNEX distributes technology products from more than 200 IT, CE, and OEM suppliers to more than 20,000 resellers, system integrators, and retailers throughout the United States, Canada, Japan, and Mexico.