The point I was making with PAYG is that there is no obligation to pay anything, but, yes, once having paid something, either by top-up or by dialling a chargeable #, then there is an obligation on the supplier to supply their services in return. Therefore the contract exists from the get-go to cover this eventuality.
Yes, I agree that in all these cases a contract always exists. Indeed it always bugs me here when users say they are 'out of contract' when all they mean is that they have exceeded the Min. Period of the contract and are now just subject to short notice.
1999: Freeserve 48K Dial-Up => 2005: Wanadoo 1 Meg BB => 2007: Orange 2 Meg BB => 2008: Orange 8 Meg LLU => 2010: Orange 16 Meg LLU => 2011: Orange 20 Meg WBC