United Kingdom

Concerns all providers: Content Lock
Prepaid SIM cards in the UK are delivered with a so called "Content Lock" in place. This is to protect children from accessing adult content.

The problem is that a whitelisting approach is used for this, meaning that everything that has not been actively approved as non-adult will be treated as adult. This can seriously interfere with your 3G operation, e.g. I could not use my instant messaging services.

The normal way to disable this feature is to enter credit card data to prove your age; but this only works with UK credit cards, and as a tourist you probably won't have one of those.

Therefore when you buy the SIM card in store insist that the lock will be removed right away (takes 1 minute). For this you may need to provide some form of ID to prove your age.

(This info is based on my experience with T-Mobile UK, but since Content Lock is apparently a legal requirement it should apply to the other providers as well.)

Vodafone UK
Vodafone has a "Pay as you Go" service.

More information

Data feature packs

 * 50p for 25MB per day
 * £5 for 250MB for 30 days
 * £10 for 500MB for 30 days

Availability
Purchase a SIM card from any Vodafone store for £5, which includes some calls. You can recharge it at their stores or many other kiosks or convenience stores throughout the country.

SIM sizes
Standard SIMs are freely available, but in Jul-Aug 2011 Micro-SIMs for PAYG were generally unavailable from most Vodafone stores throughout the UK. However, Standard SIMs can easily be trimmed down with scissors to fit the iPhone 4.

Tips
Data Sim for phone and for tablets. If you want to use data SIM in your phone you must buy it with calling and texting (10 GBP for 500 MB per 30 days). When you buy data SIM for tablets (5 GBP for 250 MB per 30 days) it will not work in your phone.

Check first for compability with your device. Vodafone "Pay as you Go" SIM cards with data packs only work on specific "Pay as you Go" devices (tried in Q4/2010 with "3 MiFi Mobile Wireless Modem" and "Vodafone Huawei E220 UMTS Modem" - confirmed by Vodafone UK customer support)!

 iPhone 4 users  will have to change the default APN settings before activating the data on Vodafone. If not, the phone will give the error "Could not activate cellular data network". The correct setting can be found on Vodafone support.

Default rate

 * 3p per minute voice
 * 2p per text
 * 1p per MB (Does not include tethering; they will block temporarily if detected)

More information

Data feature packs
When data is used up you are free to buy another pack without waiting until the end of the previously bought add on pack. After data add on is used up charges revert to 30p per MB if another add on is not bought.
 * 150MB valid for 45 days with every top-up
 * 120MB valid for 1 day for 50p
 * 500MB valid for 30 days for £5
 * all-you-can-eat data (plus 3000 texts and 300 minutes) for £15 valid 30 days

More information (This is only for smartphones.)

You can recharge using a credit card, but only if your credit card has a UK postal address.

More information (This is only for smartphones.)

Availability
Purchase from a 3 Mobile store for £10 which includes £10 credit, also available online. Extra credit can be bought from anywhere displaying the green 'top up' logo.

Mobile Broadband
Use the iPad data plan with 1 GB (£10.49) or 3 GB (£20.99). Valid for 30 days. Top-ups: 1GB £10, 3GB £15, 7GB £25. Link to iPad data plans

Link to Mobile Broadband with dongle and SIM only

You can buy a 3GB sim on Amazon UK which lasts up to 90 days for about £11

SIM sizes
Mini SIMs as standard. Micro SIMs may be available on request, (mini SIMs are able to be cut down to micro SIM size).

Nano SIMs are available.

Frequency

 * WCDMA 2100

Tethering
Yes.

Other Notes
As 3 Mobile is a purely 3G network a 3G mobile phone (with the 3G function turned on) is required, a 2G mobile phone will be cut off.

Default data rate
SIM costs 99p. £1 / day data rate. See link for more information.

Data feature packs
See link for more information, or see the gallery below.
 * 5 days: £2.50. Text WEB to 441
 * 1 month: £5. Text MONTHWEB to 441
 * 6 months: £20. Text 6MONTHWEB to 441

Fair use policy
Browse and email as much as you want. Streaming has a limit. The default data rate comes with a fair use limit of 40 MB a day. The 5 days, 1 month and 6 months have a limit of 500 MB (per month in the case of the 6 month version).

Availability
T-Mobile SIMs can be obtained for free in their own shops. Recharge at their shops, or stores and supermarkets throughout the country.

SIM sizes
The standard is a Micro-SIM which comes in a Mini-SIM spacer.

Frequency

 * GSM 1800
 * WCDMA 2100

Tethering
Yes (tested with a Nexus One / Froyo). Iphone 4 did not offer tethering with the 5 pounds a month pack, however personal hotspot feature is available.

Quality of Service
I did a trip through the UK in the area between Cambridge and Cornwall, and was very positively surprised with the speed and stability of the 3G service, even in relatively rural areas. The service in Cornwall villages was often more reliable than in big cities in other countries (e.g. Germany and France). Many of the B&Bs I visited had no WiFi, but the 3G Tethering worked so well that I hardly noticed the difference. Much recommended.

They do seem to disallow SSL encrypted access to SMTP servers though, so you need to send email unencrypted, which carries the risk of someone sniffing your credentials

-R.

From personal experience T-Mobile UK WILL NOT SUPPORT SKYPE (Sept 2012)

Additional

 * T-Mobile are currently running a promotion that allows you to get 6 months of free internet access if you buy a selected PAYG handset. The cheapest selected handset is 19.99, so buy the handset, get the promotion & put the SIM in your handset of choice. (The offer is valid until 31st August.) However it comes with some serious restrictions "You can't use your phone as a modem or use internet on your phone for peer to peer file sharing, instant messaging or making internet phone calls."


 * T-Mobile has a content filter for a lot of websites. You need an UK credit card to unlock this. If you don't have an UK credit card you can also unlock the SIM in any T-Mobile store, but not at other resellers.

Orange
Orange has a "Pay as you Go" service with a free sim card.

More Information

Default Data Rate
Maximum £2 per day

Data feature packs

 * £5 for 250MB prepaid data for 30 days
 * The Dolphin plan gives 100MB data a month

Availability
Purchase from any Orange store for free. You can charge it at their stores or several other kiosks in the country. Top up online easily.

If you are an overseas visitor, getting the Camel plan instead of Dolphin makes more sense. Paying £30 top up will give 240 free minutes international calls & cheap international calls after this. So works well coupled with the 250MB data extra.

Default Data Rate
£3 / MB. See Simplicity T&C for more information.

Data feature packs
Choose the "Text & Web" SIM tariff. Top up the following minimum in a month and get the corresponding text (to UK numbers only) and data allowance for 30 days, and calls/international text to the value of the amount of top-up. Further data allowance is available in the form of a "Web Bolt-On": £3 for 100MB, £6 for 500MB and £10 for 1GB. Text "WEB" to 21300.
 * £10: 500MB + 300 texts.
 * £15: 500MB + 500 texts.
 * £30: 500MB + Unlimited texts.

If you don't have a web allowance included in your tariff, or you don't have a web Bolt On or have not topped up a minimum of £10 with the Text & Web tariff, you'll be charged up to £1 a day to view the internet on your mobile.

Fair use policy
Unclear. The terms and conditions state that there is an excessive use policy, but not how much or for how long.

Availability
O2 Simplicity SIMs can be ordered for free from O2's website to UK addresses only or from an O2 store.

SIM sizes
According to Comparisim; Standard, Micro SIMs and Nano SIMs are all available online via O2 website. However, if a Nano SIM is needed then you can use online live-chat function to specify the required SIM type to the agent.

Frequency

 * GSM 900
 * GSM 1800
 * WCDMA 2100
 * WCDMA 900

Tethering
Not available with iPhone.

APN
APN : payandgo.o2.co.uk User Name: payandgo Password : password

Default Data Rate
50p / MB.

Data feature packs
75p for 25 MB, then 50p/MB there after, (very vague).

Fair use policy
Unclear.

Availability
Can be purchased online or from select ASDA supermarkets.

SIM sizes
Stock standard SIMs.

Network information
Branded as ASDA - Uses Vodafone network.

Frequency

 * GSM 900
 * GSM 1800
 * WCDMA 2100

Tethering

 * Unknown

Default data rate
50p / day for 25MB (Starter Tariff)

Data feature packs
See this page for more information.
 * Big Data & Texts gives you unlimited data (95GB) and 300 Texts. You have to top up your account with £10, then you call 789 and select option 3. Within a few hours the option will be activated and you'll get the free data / texts as a reward, valid for about 45 days.
 * From 1st of July 2013 you only get 1GB of data for top up your account with £10, see link below.

Fair use policy
The default data rate comes with a fair use limit of 25 MB a day. The 1 month data pack has a limit of 1 GB.

As of January 2013, multiple stores have told me data is unlimited and there is no fair use limit. I've used over 2GB in a week, many hundreds of megabytes a day with a 10pound top up in store.

--> I'll second that. I've used the Big Data tariff and we've sucked about 1GB in 3 days through a mobile router. The "What you've got left" counter went from 95GB to 94GB. It really seems to be (almost) unlimited.

Availability
Virgin mobile SIMs can be ordered online for free or in shops. SIMs are also sent to hotel adresses.

SIM sizes
Stock standard SIMs & Micro SIM

Frequency

 * GSM 1800
 * WCDMA 2100

(uses T-Mobile network)

Tethering
Tethering worked great in cities throughout England and Scotland using Galaxy Nexus, speeds of typically 3-5 megabits. Skype login seemed hit or miss, but generally worked. I don't know if they were blocking it or just skype acting up.

Note
If you want to use the Virgin Mobile SIM in a 3G Wifi Router, be aware you'll need to call the company through the SIM you're about to use for data (to activate the Big Data Pack). This may cause problems since routers are not made to call someone (duh!) Furthermore, if your 3G Router needs another SIM format than your phone, you might also encounter problems to activate the tariff.

Examples:


 * Router (like the Huawei 5531): Standard SIM


 * Phone (e.g. Galaxy S3/S4): Micro SIM Slot or even worse Nano-SIM Slots like the iPhone 5

There is no other way to activate the option than calling Virgin through the SIM. You cannot activate it via their website or SMS. In this case make sure you have an old phone available to activate the desired option.

Default data rate

 * 20p for the first 20MB, then 20p / MB for further usage that day.

Data feature packs
See this page for more information.
 * Phone: 1 month: £12. unlimited data, unlimited texts, 250 minutes.
 * Tablet or Dongle:
 * £5 for 500MB
 * £7.50 for 1GB
 * £12.50 for 3GB
 * (all per 1month)

Fair use policy
The 1 month data pack for phones is unlimited.

Availability
GiffGaff SIMs can be ordered online for free.

or with £5 free credit on activation from any member of giffgaff. The member him/herself also receives 500 points worth £5 of balance on activation of the new SIM.

SIM sizes
Stock standard SIMs, Micro SIMs can be ordered here

Tethering
Intended for mobile phone use only. See dongles/tablets for computer use.

Registration
The SIM has to be registered online together with a £10 top-up on giffgaff.com before you can use it. Get a £10 giffgaff voucher beforehand, most of the corner shops have it if you insist they look for it (it's not well known, probably also due to its strange name). If they don't have a giffgaff top up an o2 one should work too as giffgaff are an o2 MVNO. You can then use this voucher online, to register your SIM (it's explained on the site, even though sometimes not totally straight forward).

Default Data Rate
£4 / MB.

Data feature packs
monthly plan: £10. unlimited data for 3 months (fair use 500MB), unlimited texts, 250 minutes voice

monthly plan: £15. unlimited data (fair use 500MB), unlimited texts, 500 minutes voice

Fair use policy
T&C don't allow P2P, VOIP and continuos streaming AV and use SIM cards i modems (I haven't check that yet)

Lebara
Pay as you go, with free SIM card.

More information at their website.

Default Data Rate
15p per MB

Data feature packs
£2.50 / 500MB or £5 / 1GB

Travelers Mobile
For travelers to the UK, from anywhere  Travelers MobileAdded by Virtualcto

UK Plans/Products 

Travelers Mobile offers a simple plan for Travelers to the UK. Pay as you Go plans with all Calling in the UK at 10p per min. Data is 30p per MB.

Like the USA, all Travelers Mobile plans are sold with all inclusive pricing. This means Shipping, Tax, SIM and Activation is all included in the price you see. Starting as low as $ 24.95 for 30 days Pay as you Go everything included. .

Canada Plans/Products 

 Travelers Mobile offers a simple plan for Travelers to Canada. Pay as you Go plans with calling within Canada at $0.40 per minute, all texts cost $0.25 per text message and data cost between $0.06 and $0.14 per MB.

<span style="padding:0in;font-size:10.5pt;font-family:Helvetica,sans-serif;">USA Plans/Products 

<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:15.75pt;"><span style="font-size:10pt;font-family:Helvetica,sans-serif;">Travelers Mobile offers 9 plans for Travelers to the USA. All use the AT&T network, so speed and coverage is better than T-Mobile. Pay as you Go plans are for 30, 90, 180 and 365 days with all Calling in the US and to Canada at $0.10 per min. Data is $0.30 per MB. Unlimited plans are for 7, 15 or 30 days with data up to 3GB per 30 days.

<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:15.75pt;"><span style="font-family:Helvetica,sans-serif;font-size:10pt;line-height:15.75pt;">All Travelers Mobile plans are sold with all inclusive pricing. This means Shipping, Tax, SIM and Activation is all included in the price you see. Starting as low as $29.95 for 30 days Pay as you Go to 30 days unlimited calling and text plus 3GB data for $79.95 everything included. .

<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:15.75pt;">World Tra​vel

<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:15.75pt;">Travelers Mobile sells world SIMs and world data SIMs with coverage in over 200 countries.

<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:15.75pt;"><span style="padding:0in;font-size:10.5pt;font-family:Helvetica,sans-serif;">Availability '

<p class="MsoNormal" style="margin-bottom:0.0001pt;"><span style="line-height:15.75pt;font-size:10pt;font-family:Helvetica,sans-serif;">Can be purchased on the website  , or at authorized dealers across Canada.

<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:15.75pt;"><span style="padding:0in;font-size:10.5pt;font-family:Helvetica,sans-serif;">Speed '

<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:15.75pt;"><span style="font-size:10pt;font-family:Helvetica,sans-serif;">In The USA the same as AT&&T

<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:15.75pt;"><span style="padding:0in;font-size:10pt;font-family:Helvetica,sans-serif;">SIM sizes 

<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:15.75pt;"> §    <span style="font-size:10pt;font-family:Helvetica,sans-serif;">Standard, Micro SIM is available, Nano SIM cut for $5.00 extra fee.

<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:15.75pt;"><span style="padding:0in;font-size:10.5pt;font-family:Helvetica,sans-serif;">Tethering '

<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:15.75pt;"> §    <span style="font-size:10pt;font-family:Helvetica,sans-serif;">Yes

<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:15.75pt;"><span style="padding:0in;font-size:10.5pt;font-family:Helvetica,sans-serif;">Devices 

<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:15.75pt;"><span style="font-size:10pt;font-family:Helvetica,sans-serif;">Devices must be GSM unlocked and have an open SIM slot.