Buying a pre-paid phone card or mobile top up calling credit voucher anonymously

Buying a pre-paid phone card or mobile top up calling credit voucher anonymously

Whistleblowers often need to communicate with potential publishers of their disclosures in private. Cheap pre-paid mobile phones can be valuable for this either for voice calls (ideally using a pre-arranged code or pre-arranged "beeping" signals) or by using SMS text messages to arrange face to face meetings and / or whistleblower document disclosure drops or deliveries.

Such mobile phones are now cheap enough for a journalist or blogger (or Confidential Human Intelligence Source handler) to give them out to their whistleblower contacts and to pay for the top up calling credit from their end, rather than potentially exposing the identity of their source.

N.B. A whistleblower or other confidential journalistic sources should watch out for the periodic SMS text messages which are supposed to warn a mobile phone user that their mobile handset has been registered with a web based online Location Based Services tracking service - replying to such a message indicates consent for the tracking to continue Any use of such Location Based Services should be agreed up front by both parties. By default all new phones and SIM cards are blocked from using these "Adult" services so you have to contact the network e.g. at a high street mobile phone shop, for them to flag that handset as being usable for tracking (or for expensive SMS or internet pornography or sex chatlines etc.)

However, just because pre-paid mobile phones are often referred to by the Police and by lazy journalists as "anonymous" , that does not mean that they are.

The Communications Data generated by mobile phones is of three types - Location, Friendship tree (or suspect list of co-conspirators) of which number called which other number , when and for how long and your Subscriber Details.

Buying an "anonymous" pre-paid mobile phone only protects your anonymity from the central registration of Subscriber Details i.e. name and address.

See the Spy Blog "Bring and Swap" presentation given at recent CryptoParty / CryptoFestival events: (.pdf) & (.pptx)

  1. Expensive, high end smartphones are as powerful as many computers and some models e.g. Apple iPhone attempt to track your usage and identity, especially if you purchase ring tones or music online. Others, like Google Android based phones make a virtue of their Location tracking capabilities. All of these have their uses, but present dangers to a whistleblower trying to contact a journalist or blogger or other intermediary to set up face to face meetings or to arrange whistleblower document deliveries or drops. These phones can cost hundreds of pounds, so they are not usually viable as disposable "burner" phones, unless you are also involved in drug dealing or have a corporate expense account.

  2. Buy a basic, cheap pre-paid mobile phone from a supermarket etc.. e.g. VX1 Party Phone unlocked Credit Card sized basic mobile phone Samsung GT-E1080i -a very basic voice and SMS only phone with a long battery life, available for just £9 to £15 (depending on the special offers) including a free SIM card from one of seven network operators / billing services available from the larger Tesco supermarkets.

  3. You can buy a new pre-paid Mobile Phone from, for example, Tesco or Sainsburys etc., for as little as between £10 to £20 pounds

  4. Tempting as it is to buy two or more such cheap phones (for the spare battery and power charger alone), do not do so from a Supermarket. These often have arbitrary, unpublished or poorly advertised "rationing" policies in place, limiting the number of such "bargain" phones which an individual customer can buy at a time. You do not want the supermarket checkout operator to have to "consult" with the floor supervisor and have to argue about how many phones you are allowed to buy, not if you are trying to remain forgotten and anonymous in case of future whistleblower leak investigations. Obviously if you are getting a trusted third party to buy the pre-paid mobile phone for you, this may be less of a risk to consider.

  5. Do not buy the phone handset using a Credit Card or a make use of a Supermarket Loyalty Card, both of which will link to your name and address details.

  6. Do not buy mobile phone top up credit from your own bank Automatic Teller Machine or online bank account

  7. Do not top up over the mobile phone e.g. Vodafone 2345, using your own Credit Card / Debit Card.

  8. Use cash to buy a top up credit voucher from a shop or supermarket, ideally avoiding CCTV cameras.

  9. Some mobile phone networks e.g. Orange promote the use of plastic swipe card top up cards, which firstly need to be registered to the SIM card and phone number you are using. Obviously these should normally be avoided, but there may be circumstances where they are useful e.g. if journalist or lawyer or blogger (or Confidential Human Intelligence Source handler) gives a mobile phone to their whistleblower source / confidential contact, they can conveniently top up the phone credit remotely at a supermarket checkout or also via the online website.

  10. It is common practice in the Third World for people in cities (where there are mobile phone shops) to purchase mobile phone calling credit vouchers and then to SMS text message the 12 digit one time code number to their relatives who live in country villages etc. Therefore you can and should buy top up calling credit vouchers at several different locations, ideally getting someone else to do so on your behalf.

  11. You could get a friend or relative to buy top up calling credit vouchers for you and then communicate the 12 digit code to back to you, using other communications channels. At a push they could phone you up on a different mobile phone and read the numbers off to you, but secure, encrypted email etc. would be better.

  12. Do not send the 12 digit calling credit top up voucher numbers either via unencrypted, normal, internet email or by SMS text message. Nominally the Interception of the content of such electronic communications would need a warrant signed by the Home Secretary, and it is unlikely that these would be noticed before a whistleblower leak story was published, but they may well be available to a later Leak Inquiry investigation.

  13. Do not switch on or Activate the new mobile at home or at work, or when your "normal" mobile phone switched on.The first activation of a mobile phone has its physical location specially logged, and it is easy to see what other phones are active in the surrounding Cells at the same time i.e. your own "normal" mobile phone.

  14. Destroy the paper copies of any top up calling credit vouchers after you have used them, they are of no use to anyone except a future Leak Inquiry investigator - they give details of time, date location of where they were purchased. The voucher number which can obviously be cross referenced to the SIM card and Phone that they were used to top up. If you are a journalist or police officer etc. claiming the cost of this top up calling credit on expenses, then you only need receipts for the amount of money spent, you should not hand over originals or copies of the actual vouchers themselves.

  15. Do not Register your pre-paid mobile phone, despite the tempting offers of "free" phone credit.

  16. Second hand mobile phone handsets can be bought online, but this obviously leaves a Credit Card or PayPal etc. electronic transaction trail, so do not bother.

  17. Second Hand mobile phone handsets are often available at non-mobile phone network shops or at counters within a larger shop, usually offering Mobile Phone Unlocking, repairs, mobile phone accessories like coloured casings etc. and spare batteries and chargers etc. which the mainstream Mobile Phone shops no longer bother with. They often cater to local immigrant communities who have foreign registered mobile phones which they want to use ion UK networks. Phone Unlocking from one network to another is not illegal, but re-programming the IMEI is (up to 5 years in prison even for advertising such a service), because of the legal fiction that stolen mobile phones could only ever be unblocked in the UK, rather than overseas as they have always been.

    The disadvantage with this sort of purchase is that they are often more expensive than a new low end Supermarket phone and they could have been previously used by drug dealers or illegal immigrants etc. who are already being tracked electronically by the authorities. These shops do not usually have extensive CCTV camera video recordings like supermarkets, but they are likely to be regularly questioned by the Police etc. so the shop assistant / proprietor may quickly "cooperate" with any Leak Inquiry investigation, if you are in any way memorable.

Pre-paid cards for public phone boxes

Exactly the same precautions are need for other pre-paid phone cards, such as those which are used in public phone boxes, to replace cash or coins.

Obviously do not make a call using your own Credit Card (which can be done in some public phone boxes, or, on some airliner flights).

All of these have unique serial numbers which can be used to link together a pattern of phone calls, so if you do choose to use one for contacting a journalist or politician or whistleblowing supervisory authorities or for any such people to contact their whistleblower contacts, then no other phone numbers such be used, even if there is still credit left on the card or the voucher. i.e. do not call your family or friends or work colleagues using the same pre-paid card card (or mobile phone) as which you use for whistleblower communications.

About this blog

We know that there are decent, honest, trustworthy individual politicians, civil servants, law enforcement, intelligence agency personnel and broadcast, print and internet journalists etc., who often feel powerless or trapped in the system. They need the assistance of external, detailed, informed, public scrutiny to help them to resist deliberate or unthinking policies, which erode our freedoms and liberties.

Some of these people will, in the public interest, act as whistleblowers, and may try to leak documents or information to the mainstream media, or to political blog websites etc.

Here are some Spy Blog "Hints and Tips", giving some basic preecautions, and some more obscure technical tips, which both whistleblowers, journalists, and bloggers need to be aware of, in order to help preserve the anonymity of whisteleblowing or other journalistic sources, especially in the United Kingdom, but applicable in other countries as well.

Whistleblower anonymity may not always be possible, or even necessary, forever into the future, but it is usuially crucial during at least the early stages of a "leak", whilst it is being evaluated by others, to see if it merits wider publication and publicity.

Email & PGP Contact

Please feel free to email your views about this blog, or news about the issues it tries to comment on.


Our PGP public encryption key is available for those correspondents who wish to send us news or information in confidence, and also for those of you who value your privacy, even if you have got nothing to hide.

You can download a free copy of the PGP encryption software from
(available for most of the common computer operating systems, and also in various Open Source versions like GPG).

We look forward to the day when UK Government Legislation, Press Releases and Emails etc. are Digitally Signed so that we can be assured that they are not fakes. Trusting that the digitally signed content makes any sense, is another matter entirely.


Tag Cloud

CryptoParty London

CryptoParty London

Most months there is a CryptoParty London event. where some of these Hints and Tips and other techniques are demonstrated and taught.

Usually at:

Juju's Bar and Stage 15 Hanbury St, E1 6QR, London

Follow on Twitter: @CryptoPartyLDN

Syndicate this site (XML):


Campaign Button Links

Watching Them, Watching Us, UK Public CCTV Surveillance Regulation Campaign
UK Public CCTV Surveillance Regulation Campaign

NO2ID Campaign - cross party opposition to the NuLabour Compulsory Biometric ID Card
NO2ID Campaign - cross party opposition to the NuLabour Compulsory Biometric ID Card and National Identity Register centralised database.

Gary McKinnon is facing extradition to the USA under the controversial Extradition Act 2003, without any prima facie evidence or charges brought against him in a UK court. Try him here in the UK, under UK law.
Gary McKinnon is facing extradition to the USA under the controversial Extradition Act 2003, without any prima facie evidence or charges brought against him in a UK court. Try him here in the UK, under UK law.

FreeFarid_150.jpg - Kafkaesque extradition of Farid Hilali under the European Arrest Warrant to Spain

Peaceful resistance to the curtailment of our rights to Free Assembly and Free Speech in the SOCPA Designated Area around Parliament Square and beyond

Parliament Protest blog - resistance to the Designated Area restricting peaceful demonstrations or lobbying in the vicinity of Parliament.

Petition to the European Commission and European Parliament against their vague Data Retention plans
Data Retention is No Solution Petition to the European Commission and European Parliament against their vague Data Retention plans.

Open Rights Group

renew for freedom - renew your passport in 2006
Renew For Freedom - renew your Passport in the Summer Autumn of 2006.

The Big Opt Out Campaign - opt out of having your NHS Care Record medical records and personal details stored insecurely on a massive national centralised database.

Tor - the onion routing network
Tor - the onion routing network - "Tor aims to defend against traffic analysis, a form of network surveillance that threatens personal anonymity and privacy, confidential business activities and relationships, and state security. Communications are bounced around a distributed network of servers called onion routers, protecting you from websites that build profiles of your interests, local eavesdroppers that read your data or learn what sites you visit, and even the onion routers themselves."

Tor - the onion routing network
Anonymous Blogging with Wordpress and Tor - useful Guide published by Global Voices Advocacy with step by step software configuration screenshots (updated March 10th 2009).

Amnesty International's campaign

BlogSafer - wiki with multilingual guides to anonymous blogging

NGO in a box - Security Edition privacy and security software tools

Home Office Watch blog, "a single repository of all the shambolic errors and mistakes made by the British Home Office compiled from Parliamentary Questions, news reports, and tip-offs by the Liberal Democrat Home Affairs team."

Reporters Without Borders - Reporters Sans Frontières - campaign for journalists 'and bloggers' freedom in repressive countries and war zones.

Committee to Protect Bloggers - "devoted to the protection of bloggers worldwide with a focus on highlighting the plight of bloggers threatened and imprisoned by their government."

wikileaks_logo_low.jpg - the controversial "uncensorable, anonymous whistleblowing" website based currently in Sweden.

Public Concern at Work - "(PCaW) is the independent authority on public interest whistleblowing. Established as a charity in 1993 following a series of scandals and disasters, PCaW has played a leading role in putting whistleblowing on the governance agenda and in developing legislation in the UK and abroad. All our work is informed by the free advice we offer to people with whistleblowing dilemmas and the professional support we provide to enlightened organisations."