Okay so i'm new to this phone plan business. If I were to go about buying an Iphone 4s, would it be more expensive depending on the plan it is with? For example Bell,Telus,Rogers, ect.

AND how would I start paying the monthly fees when buying it off of someone who has it on a plan?

Example: I buy an Iphone 4s off of Bob. Bobs iphone is with telus. Bob pays the telus bill every mounth.

HOW does Bob stop paying telus and I start?

I think the plan stays with Bob. You need an unlocked phone you can start your own plan on. I think all the phones sold hear are unlocked.

^You would have to read the terms and conditions of Bob's contract with Telus.

Telus sells iPhones with or without a contract.

I suspect Bob's contract prohibits resale or any subsequent transfer (i.e. sub-lease).