Question : Problem: What type fo Cable is used?

I have a ATT&T modem ( DSL) and I want to connect it to a router ( linksys) which cable should I use?
Cross over cable or Strightthrought cable?  I would think Cross over cable but not sure.

Thanks for your help guys...

Answer : Problem: What type fo Cable is used?

Most modern devices are auto-detect, but for the record like devices ( such as 2 switches) require a cross-over cable, and dislike devices ( a switch and a router) require straight through.
Most modems => routers use straight through, but some especially combined modem/router units use cross-overs. Best bet is try it. If the lights do not illuminate, you have the wrong cable.