Except that, on second thoughts ....
If the PAYG deal does indeed include the extra hundreds of minutes per month from a nominated postcode in return for topping-up by a certain amount each month, the comparison is not quite so straightforward.
So if, for example, £15 per month top up were sufficient to cover calls made from locations other than the nominated postcode, a 16Gb 'phone over 18 months would be marginally (£40) cheaper on PAYG than the £35 per month contract - and £10 per month cheaper every month thereafter.
Hmm .... clearly a bit harder to decide than I first thought!![]()
I thought about trying to do a least cost calculator but don't have the time... plus I'm not sure my javascript is up to it. I chickened out and added the thresholds for the PayG tariff choices and left it up to the user to sort out!
btw. Calling once a week + Favourite place you get 150 minutes for £15 and 1000 minutes from your favourite place.
Calling every day gets you 60 minutes (2 minutes a day!) - so when you call is kinda critical.