Three’s 321: The UK’s Cheapest PAYG Tariff at 3p/minute, 2p/text and 1p/MB

March 21st, 2014

Three is currently offering the UK’s cheapest Pay As You Go tariff. Calls cost 3p/minute, texts cost 2p each and data costs 1p/MB.

Three 321 Pay As You GoThree has revamped their Pay As You Go offering. Their latest tariff, which is called 321, has the lowest rates we’ve ever seen on a UK Pay As You Go tariff. Calls are charged at 3p per minute, texts at 2p each and web browsing at 1p per megabyte. You’ll also get a free data allowance of 150MB whenever you top-up. The free data lasts for a maximum of 30 days.

The 321 tariff is ideal for light users: there’s no standing charge and you’ll only pay based on what you actually use. The bonus free data allowance can also be handy for anyone with a smartphone: you’ll be able to use instant messaging apps (e.g. WhatsApp) and browse the web occasionally without paying a penny.

In this article, we review the 321 tariff. We’ll look at pricing and how 321 compares to rival offerings from networks such as giffgaff. We’ll also look at the pros & cons of the tariff and how to keep your phone number when switching to the tariff.


ThreeAccording to Three, the 321 tariff offers “game changing rates” on Pay As You Go. Unlike many other mobile networks, Three doesn’t require you to buy a monthly bundle to get the best value. Instead, you’ll get great calling rates without a fixed monthly charge and you’ll only pay for what you actually use. Calls cost 3p per minute (any network, any time), texts cost 2p each and data costs 1p per megabyte.

As a bonus for anyone with a smartphone, Three will give you 150MB of free mobile internet whenever you top-up (£5 is the smallest available top-up). The free internet allowance expires after 30 days (see heading “Free Internet Use” on Three’s Pay As You Go Terms & Conditions). After using up the free internet allowance, you’ll pay just 1p/MB when accessing the mobile internet. The average smartphone user can expect to pay around 10p/day.

Calling Rates:
Voice Calls 3p/minute (any network, any time)
Calls to Voicemail 3p/minute
Messaging Rates:
Text Message (SMS) 2p
Picture Message (MMS) 31p
Video Message 38p
Internet Rates:
Mobile Internet 1p/MB
Free Allowance 150MB free allowance (valid for 30 days)

The prices in this table are stated for UK-to-UK only. If you’re roaming, making international calls or calling a special number (e.g. 08 & 09 numbers) higher charges will normally apply. Source for pricing information:

Charges for Mobile Data

SmartphonesThere are many factors influencing your consumption of mobile internet data. For instance, it depends heavily on whether you connect to wi-fi at home, the amount of web browsing you do and also the types of application installed on your phone.

As a general rule of thumb, the average smartphone user consumes around 10MB of data everyday. This assumes you avoid bandwidth-heavy services such as online radio and online video. At 1p per megabyte, the average smartphone user would pay 10p/day. That’s equivalent to £3/month after using up your free data allowance.

For heavy smartphone users, data charges can be substantially higher. The following table provides a rough guide on how much it’ll cost to use your smartphone on 321:

Activity Approximate Cost
View 100 simple webpages (mainly text) 10p
View 100 rich webpages (mainly text) 33p
Send 1,000 instant messages/e-mails (no attachments) 1p
Downloading an MP3 5p
Watching Online Video (15 minutes) £1.25
Skype Voice Call (15 minutes) 9p
Skype Video Call (15 minutes) 60p
Online Radio (1 hour) 65p
Downloading/Updating an Application 7p
Average User (10MB/day) Approx. 10p per day

Calculations based on a price of 1p per megabyte. Source of estimates: O2 [1, 2]. A typical MP3 file is 5MB in size. Our testing found a Skype mobile voice call consumes around 0.55MB/minute (70kbps). A Skype video call consumes around 4MB/minute (500kbps). Online radio calculation assumes 128kbps bitrate. Average size of app is 6.1MB (based on a sample of the top 20 Android apps).

For more information on mobile data usage, see our in-depth guide to download allowances. We’ve also provided some information on how to track your mobile data usage. Heavy data users who consume more than 500MB per month will often find better value on a SIM only deal.


iPhone 5c

Apple’s iPhone 5c: One of the handsets available on 321.

Three currently offers a choice of 52 handsets on Pay As You Go. Popular options include:

A full list of available handsets can be found on Three’s website. You can also buy a SIM-free smartphone from retailers such as Amazon. They’re sometimes cheaper and you can use them on Three by ordering a 321 SIM card.

Using Your Current Handset

If you already have a phone you’d like to keep, Three has a 321 SIM card that slots into the back of your old handset. If your handset was previously used on a different mobile network, you’ll need to make sure it’s first unlocked before you can use it on Three. We’ve got a step-by-step guide on unlocking your iPhone, unlocking your Samsung Galaxy and unlocking your BlackBerry handset.

N.B. In order to use your handset on Three, it must support either 3G or 4G mobile networks. Three doesn’t offer any 2G coverage. Most modern handsets are compatible with 3G: the main exception is incredibly basic and low-cost handsets (e.g. a classic style Nokia). If you’re in any doubt, it’s worth checking with your handset manufacturer.

Keeping Your Phone Number

Transfer Phone Number to ThreeIf you’re switching to Three, it’s a straightforward process to keep your old phone number.

To begin the process, contact your old network and ask for a PAC Code. This will authorise the transfer of your number to Three’s 321 tariff. After ordering and activating your 321 SIM card, you’ll need to submit your PAC Code through Three’s online form. Providing this is done before 5pm, your phone number transfer will take place on the next working day.

For step-by-step instructions, please select your current mobile network:

PAC Code Finder: Transfer Your Phone Number to Three

Your current network provider:

  More Options


Mobile MastThree currently offers 98% UK population coverage. You can use their online coverage checker to see whether your area is covered. We recommend having “indoor & outdoor coverage” (look for dark blue).

Tethering Restrictions

Tethering is not permitted on the 321 tariff. In order to tether, you’ll need either a Pay Monthly tariff or a tethering add-on (see Three’s rules on tethering and portable hotspot usage).

4G Connectivity

Customers on the 321 tariff have access to 4G at no extra charge. You’ll need a 4G-ready handset and you must live within a 4G coverage area.

Inactivity Period

Clause 9.1 of Three’s Terms & Conditions for Pay As You Go states that services may be suspended if you don’t top-up or make a chargeable event in a six month period. In order to stop your account from being closed, you must either make a phone call, send a text message, send a picture message (MMS) or browse the internet at least once every six months. Aside from this, any credit that you add to your account should not expire providing your account remains active.

For more information, see our guide to PAYG inactivity periods & credit expiry.

More Information

For more information on 321 tariff, please see Three’s website. You can also order a 321 SIM pre-loaded with £10 of credit.


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About Ken

Ken Lo

I'm a freelance writer specialising in mobile technology. I've been blogging at Ken's Tech Tips since 2005 with the aim of demystifying mobile technology for the rest of us.

Before writing about mobile technology, my background was in space & atmospheric physics. I have also worked in software development. Nowadays, I help companies to explain mobile technology to their customers. Please check out my portfolio or get in touch for more information. I'm also on Google+.

Your Comments

We'd love to hear your thoughts and any questions you may have. So far, we've received 23 comments from readers. You can add your own comment here.

  1. Barbara Fisk said:

    I think that this 321 tariff sounds great but I cannot find out if there is a minimum call charge or call set up charge, I know some mobile companies do this. Can you help please. Thanks

    1. Ken Lo
      Ken replied:

      Hi Barbara,
      On Three, the length of all phone calls will be rounded to a full minute – you’ll then be charged for the usage at 3p/minute. There isn’t a separate charge for setting up the call. To give a few examples:
      – A 1 second phone call will be charged as 1 minute (3p)
      – A 59 second phone call will be charged as 1 minute (3p)
      – A 70 second phone call will be charged as 2 minutes (6p)
      If you’d like to go back to the original source, read the small text on page 2 of their Pay As You Go price guide.
      Hope this helps to answer your question!

      1. Barbara replied:

        Thank you for your help. I will definitely give 3’s 123 a try.


  2. Jan said:

    Hi Ken
    I’m a very light user and have just received an iPhone 4s as a birthday gift, I am currently on O2 payg and have turned auto updates off as it was using up all my credit I am now considering changing to Threes 321 payg however Threes network coverage for my area is showing pale blue for indoor coverage, would installing Threes in touch app be advisable to overcome any indoor issues. Thanks Jan

    1. Ken Lo
      Ken replied:

      Hi Jan,
      Thanks for your comment. If you go with Three, then I’d certainly install the inTouch application. Do note however, you will still experience reduced battery life when choosing a network with poor indoor coverage. The inTouch app also provides a less satisfactory experience compared to normal calling. So if possible, I’d still try and find a network which offers indoor coverage for your home. Take a look at my article on coverage for more discussion on this issue – a potential option for you could be getting a SIM card from giffgaff (free). The coverage is identical to O2 but costs are substantially lower.
      Hope this helps,

      1. Roza Elfassy replied:

        Hi, So is it cheaper to take a giff gaff bundel , or three 321 fir calls & texts, when visiting uk for bussinness 4 times a year?

        1. Ken Lo
          Ken replied:

          Hi Roza,
          It would depend very much on how you actually use your phone (i.e. the length of time you stay in the UK and your mobile usage during that period). With the giffgaff bundles, you’d obviously be paying for a whole month at a time. With 321, you’d only pay based on your usage and your credit should remain until you visit the UK next (providing of course you don’t allow the SIM card to be inactive for 6 months). If your visits to the UK last for under 2 weeks, I’d say 321 is probably going to be cheaper. If you’re coming for more than 2 weeks and using your phone fairly often then giffgaff goodybags may work out to be cheaper.
          Hope this helps,

          1. Roza Elfassy replied:

            Thanks. I stay a week so 321, is the choice. Thanks

  3. KGB said:


    Would the 321 sim card work purely for data usage on my Nexus 7 2013 LTE tablet?

    1. Ken Lo
      Ken replied:

      Hi KGB,
      Thanks for your comment. There’s no reason technically why the 321 SIM card wouldn’t work in a tablet. However, this is prevented by section 5.3 of Three’s PAYG terms and conditions:

      5.3 Each SIM may only be used in Devices:
      (b) which are in the Device category it was provided to you for, for example, you must not use a SIM for a
      phone in a tablet or dongle

      For the Nexus 7, you’ll need to get one of Three’s mobile broadband tariffs. It’s £10.49 for 1GB of data (this works out at only slightly more than 1p/MB).
      Hope this helps,

  4. Gavin said:

    I put my Mum on this tariff. Used to put £20 on a mouth on her phone, when on T-mobile standered pay as you go. Now £10 pound lasts her over a month. T-mobile did do bundles which would of worked out about the same, but where to complicated for her. So this simple package sued her well. Only problem she has is topping up, so have to type in E vouches into her phone. On Tmobile she was given a card that would topup her phone automatically, but not available on There. However the saving are worth the hassle.

    Also had to get her a new phone a Three only has a 3g network and her old phone would only work on 2G. Got her the Nokia C1 and suets her well with a big screen, and transitional numeric keypad.

  5. Alex said:

    I switched yesterday from an Orange contract to Three’s 321 PAYG, as it works out cheapest for my usage. I had to top-up £10 for the first top-up though subsequent top-ups can be as low as £5. With my initial top-up of £10 I got 150Mb free as mentioned in Ken’s article but I was surprised to also receive 600 free texts; both lasting 30 days. I am also pleased with Three’s coverage where I’m living, quite a fast connection. So I recommend Three.

  6. Judy said:

    Hi Ken,

    I’ve just moved from Ovivo to Three 321. Though a very low user, I think the charges for data could be higher than you suggest. I’ve been told that (once my initial free data allowance has expired) I will be charged 1p each time my phone contacts the internet (e.g. to synch email) so that, for example, I could be charged £1.00 if my phone makes contact 100 times, even if the total data consumption is only, say, 2MB.

    If this is right, if on a 321 tariff, you need to switch off any autosynch and, to keep control, switch off the data connection, only switching it back on when needed.

    It may be I’m wrong: it was possible to read and send emails on my phone using the mobile phone signal before there was any credit on the phone.

    1. Ken Lo
      Ken replied:

      Hi Judy,
      Thanks for your comment. I’m not aware of any minimum charges when your phone connects to the internet. On most smartphones today, an always-on connection will be maintained to the internet. Hence, there wouldn’t be a new data session when syncing your e-mail, checking the weather, etc. If the total data consumption is 2MB, you should only be charged 2p for all of the usage.
      With regards to being able to read and send e-mails without any credit, this is a rather interesting situation! It shouldn’t be possible (unless you were using wi-fi at home). Alternatively, there’s the 150MB of free data every time you top-up your SIM card. You may have been using the free data allowance included on a previous top-up.
      Hope this helps!

      1. Judy replied:

        Many thanks for your reply. My free allowance has now expired, so I’m able to confirm you are right about the charging. So far I’ve just used the phone for checking emails and sending the odd email and have not yet spent my fist penny. It seems the telephone help people at Three gave me duff advice.

        1. John replied:

          So what did u find. Does it charge for time it connects to internet. or when u reach 1mb then it charges 1p.

          1. Ken Lo
            Ken replied:

            Hi John,
            Three will charge 1p to your account after you’ve used 1MB of data. There’s no charge for the amount of time spent connected to the internet.
            Hope this helps,

          2. Judy replied:

            It’s working well for me. I mostly use the phone for checking emails and I only get charged when total use adds up to 1MB. I think it’s a bargain for low users. (Though not as good as Ovivo which I was on before and free.)

  7. Phil Dudd said:

    Hello Ken
    Thankyou in advance for your support, indeed for all your work on this informative site.
    My question is with regards to 0845 0870 numbers. etc…
    i was caught out a while ago when i used all my top up for a bundle and found that i needed separate credit for these type of numbers.
    specifically my question is with regards to:
    three 321 tariff, and orange (any animal pack)
    do you know how they stand with these numbers.
    To date i’ve only found vodafone support these unlimited for an extra payment of around

    1. Ken Lo
      Ken replied:

      Hi Phil,

      Thanks for your comment!

      With regards to Three, you can check their special call prices via this link. For 0845 and 0870 numbers, it’s a rather hefty 35p/minute :(

      For Orange, the Pay As You Go price guide can be found via this link. On page 16, you’ll see it costs 12p/minute to call 0845 and 0870 numbers.

      With regards to cutting costs, it’s definitely good to find a non-geographic number (e.g. your bank might list a number you’re able to use when calling from outside the UK – you can often use this number within the UK too). There’s also websites such as SayNoTo0870. Finally, most government departs have switched to using 0345 – using the new number should save a ton in calling costs.

      Hope this helps!


  8. gill hutson said:

    Well hubby is paying 35p per minute with orange. Hope his phone is unlocked and if so will go on to this great tarriff rates for occasional user.

  9. Jim said:

    Just ditched Virgin’s “Simply 8″ (eight pence for calls and for texts). Going with 321 or staying with Virgin? A no brainer.

  10. Pete Forman said:

    I don’t think that this is a new tariff as such, it is a reduction of the rates for the existing “Pay As You Go on Three”. That said, new customers would be buying a 321 SIM.

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