So I brought a Lenovo A3500-HV tablet from PB Tech.

Before pulling the trigger, I asked the Salesman "Does this work on the Spark Network" and got the response yes it will.

Now I'm having difficulty, Tried 3x Different sim cards, and get No Service, or Emergency Calls only.

Where I'm getting confused is...
this link on GSM Arena says it supports "2G" GSM 850, but doesn't list 2100. Strange.
the box that it came in says: wwan: WCDMA
Haven't heard that term thrown around in a long time.

Am I missing something or is there an extra step/setting, 'Register on Network' or some such that I need to fiddle with?

Any advice from those who know would be appreciated.