I'm sure I saw an O2 ad recently that promised existing customers the same deals as new customers. Sadly, it doesn't look like that applies to the new O2 tariffs, unless you renew of course.Yes, the new O2 monthly tariffs are being offered to new and upgrading customers and are both 'simple' and 'flexible' according to the network. Essentially, instead of offering a set combination of minutes, texts and MBs of data, you can now 'tailor' your own tariff to your needs. So if you're a heavy data user, opt for the higher-end 1GB (£10) deal for that. Or if you send just a few emails, sign up for a 100MB (£3) data package, perhaps with a deal leaning more towards calling or texts if that's your thing.Interestingly, in light of the recent iOS 4.3 upgrade furore, O2 has now chosen to include internet tethering as part of any deal. If you've not encountered it before, tethering allows you to use your phone as a modem to connect your laptop to the internet. Some networks have been demanding extra fees to allow the iPhone to do this. With a number of Android phones also offering this facility wirelessly too right now, it seems like O2 has been forced to act. Or simply wants to lead. Here's hoping that the other networks follow its admirable example. O2's deal is 'completely included in our data allowances', which apparently equates to £7.65 additional value built into each tariff.Finally, O2 has launched shorter, 12-month contracts for existing customers, so you can benefit from the latest handsets when they land. Once upon a time this was standard, but contracts have gradually creeped up to two years. Not great when the iPhone renews every year and new Android phones launch every week. Presumably, like the Tesco 12-month deals, you'll be asked for a heftier upfront fee for the handset.See the O2 website for details of all the deals. If you want one - or want to upgrade to a new contract - you can do that online or you can drop into an O2 store to sort it out.