Been with O2's "Pay Upfront For Life" tariff for the last 12 years or so and since i stick within my 50 inclusive minutes/month i typically pay nothing.

I was quite happy with this arrangement but unfortunately over the past couple of months O2's signal has become very intermittent. It's not a problem with my phone as other O2 users in the area are experiencing it too (though i couldn't find anything on O2's site about problems).

So i need a new provider but after more than a decade of paying very little for mobile service the typical >£10/month contracts seem extortionate.

Found 3's SIM Zero tariff, which charges no fee per month but 20.4p/min for calls (still much cheaper than non-inclusive calls on my O2 tariff). Seems good and the coverage map indicates i have good coverage in my area, but it's a 3G-only provider and i prefer to switch off 3G to maximise battery life (currently get 7 days on my ZTE Blade).

Talk Mobile has a £1/month contract with 25 minutes and 50 texts which would be more than enough but it's about £1/month too much.

So, are there any 2G providers that offer a £0/month contact with a pay as you use model, or is 3 my best option?

Just how little do you plan on using your phone?
The 3 deal might be £0/month, but at 20p per minute will very quickly mount up if you do use it very much. There are PAYG options available for 6p/min (icardmobile).

However, if you are complaining about TalkMobile's £1/month tariff being £1/month too expensive, I take it you are looking to hardly use you phone at all but still prefer a monthly billed account. That £1/month deal includes 25 minutes of calls - to any network.

Vectone do a similar £1/month deal - theirs includes 30 minutes, 30 texts and 30MB of data each month.

What usage are you actually looking for? Three's £0/month is only better than Talkmobile or Vectone's £1/month where you are sure you are going to use less than 5 minutes in the month.

Run-on rates (what you pay after inclusive minutes) can be an issue with these deals - Talkmobile charge 30p/min and Vectone 20p/min, so something like The Phone Co-op's 7p/min tariff might worth out better for variable usage (although they do charge £2/month for absolutely no minutes or texts).

No minutes would cost £0.00 on 3 Zero, £1.00 on TalkMobile, £1.00 on Vectone and £2.00 on Phone Co-op.

25 minutes would cost £5.10 on 3 Zero, £1.00 on TalkMobile, £1.00 on Vectone and £3.75 on Phone Co-op.

50 minutes would cost £10.20 on 3 Zero, £8.75 on TalkMobile, £5.00 on Vectone and £5.50 on Phone Co-op.

75 minutes would cost £15.30 on 3 Zero, £16.00 on TalkMobile, £10.00 on Vectone and £6.25 on Phone Co-op.

3's Zero tariff only wins on consistently very low/no usage
TalkMobile and Vectone are equal on usage from 5 to 25 mins
Vectone win for usage between 25 and 53 minutes.
The Phone Co-op win for usage over 53 minutes and are always within £3 of the cheapest option for any usage, making them worth considering for wildly variable usage as you'll pay 7p/min for extra minutes and not 20p/min (3/Vectone) or 30p/min (Talkmobile)
However, consistent usage of 50 minutes of more would be much better on a different deal - such as 100 minutes (and unlimuted texts and 100MB of data) for £5/month from Vectone.

it's £0 a month, plus free Skype and Windows messenger, sim or micro sim and you can add addons, like the £5 internet addon, so it's ideal for tablets etc.

Sim zero will suit some people specifically, maybe as a 2nd phone or emergency use or very light use, tablets, 2nd devices.

As others have said sim zero is only really ideal for incredibly light use or for incoming calls only. Another use for it is for people with credit problems as it still reports to credit reference agencies even though there is a zero bill.

Frankly the talk mobile offer sounds like an incredible deal for light use and I'd be snapping their hands off if I was a light user

Most of the major networks lowest sim only tariffs come in at approx £10 a month

The O2 status checker is now showing that a mast in my area is having problems, so now that they're acknowledging there's a problem i've some hope that it'll eventually be fixed and i can go back to my PUFFL deal.

25 minutes per month is more than enough, and many months i don't use anything. Vectone is no good as they use O2 so i'd have the same problem.

Talk Mobile would be best if i were actually making outbound calls, but i could probably get by without making any mobile calls until O2 fix the mast (hardware SIP phone at home and softphone on my mobile usually within a WIFIed environment).

Since the SIM Zero costs nothing i went ahead and ordered one anyway. I'll see how it goes. The free Skype is not really interesting to me since i've always preferred a proper SIP-based service for VoIP, but it might be interesting to setup Asterisk with a Skype channel and see if i can get it to simultaneously ring my mobile and SIP phone.

Thanks for the help.

I don't see why you want a contract type option. Just get pay as you go? Both Asda and Lebara Mobile operate on Vodafone. Asda was 8p calls, 4p texts the last time I checked.

They are 6p and 10p now, but that's not necessarily the point. As I already explained you get free Skype and live messenger, if you are a light user there is no need to top up £10 or whatever, you can top up when you want to use it and then not use it for a while.

You can also add addons like the £5 data addon and you can get micro sims on it too, so it's very good for a 2nd phone or device, or light use.

You also never have to bother topping up and messing around. I can see the benefits, but it's not for everyone. If you just want the cheapest, then talk mobile beats Asda and Giffgaff.

At 6p/min for mobiles and 3p/min for landlines, icardmobile is very likely to beat all three of those networks for plenty of users (texts are, admittedly, 1p more than talkmobile at 5p each)

Vectone use T-MOBILE, and now also allow 2G roaming onto the Orange signal in the UK.