Could use some advise...please!

So I recently bought a sch-a870,it's my first cell phone.
I know next to nothing and could use some help.The phone wont recieve any incoming calls unless it's set to "analog".could someone tell me why?and whay analog means.Also when it is set a analog,it say's battery consumption is higher.How much higher?
Also what quality is the phone I have bought?I mean is it a ok phone ,really good or just run of the mill?
Any help would be great.
Thanks
Aaron

Bump,...sorry but I could really use some help.I know my questions are quite simple but I am a complete rookie with these devilish contraptions.....anyone?