[andy]

Contracts with only the same network and landlines have tended to fade away over the last few years, to the point where if there's just the one set of minutes defined, they will all be cross-network, so for simple contracts your friend is right.

Subsidiary bundles have also been appearing, but perhaps mainly as bonuses on more expensive contracts, particularly as more free calls to the same network or to landlines. O2 do this sort of thing, or some Orange options

On 3 contracts, or their very similar payg bundles, there is a bundle to cross-network and landlines, with 300 extra minutes to call 3. So calls to 3 would use these first then the main bundle

But without those extra complications, and if not needing really lots of minutes, I'd say broadly similar cross-network packages is a reasonable approximation

There are some differences between contracts in the shops and online - it seems to be possible to get more minutes by going direct. Or there are short notice contracts without a phone, starting at typically ~200 minutes for £15. But of course kids and teenagers might want trendy new phones all the time ...

Other considerations are cashback deals, where the dealer rebates part of or even more than their commission, but they're a bit in disrepute as some dealers have gone broke by bad underwriting of just what proportion of customers will remember to send back instalment claims (e.g. 6 vouchers to send in over 18 months, at which point I gave up). I really wouldn't recommend this though for someone unwilling to devote time to boring study of which dealers are reliable and then good self-reminders

At the moment, 3's 1100 minutes or texts deal (plus the 300 minutes to 3, plus free Skype calls on suitable phones), currently reduced to £20 a month, looks more than most people would ever need.