A SIM lock, simlock, network lock or subsidy lock — not to be confused with PIN or PUK code — is a capability built-in to GSM phones by mobile phone manufacturers. Network providers use this capability to restrict the use of these phones to specific countries and network providers. Currently, phones can be locked to accept only SIM cards from one or more of the following:
In most countries, most mobile phones are shipped with country and/or network provider locks. In addition, these locked phones tend to have firmware installed on them which is specific to the network provider. For example, if you have a Vodafone or Telstra branded phone in Australia, it displays the relevant logo and may only support features provided by that network (e.g. Vodafone Live!). This firmware is installed by the service provider and is separate from the locking mechanism.
You can unlock most mobile phones to work with any GSM, such as O2 or Orange (in the UK) but the phone may still display the original branding and may not support features of your new carrier. Most phones can be unbranded by uploading a different firmware version, a procedure recommended for advanced users only.
Currently there are 2 cases (VTB-VAB NV v Total Belgium NV and Galatea BVBA v Sanoma Magazines Belgium NV), in front of the European Court of Justice that will determine whether the laws in Belgium are forbidden under Directive 2005/29/EC The Unfair Commercial Practices Directive. If successful, Belgium must repeal the anti-bundling law.
Belgian Enterprise Minister Vincent Van Quickenborne is currently undergoing steps to repeal the laws in question, regardless of the European Court of Justice ruling. If successful, Singapore will be the only country in the world that outright forbids SIM locking and contract/phone bundling.
US and UK don't have any SIM locking laws, but American and British carriers usually offer unlocking codes voluntarily.
In the United States, one of the two national GSM carriers, T-Mobile , will unlock your handset if you have an active account in good standing for at least 90 days. The other, AT&T Wireless , will usually do so once you have concluded your contract, but may also unlock the phone in some other situations as well.
In a 2006 submission to the US Library of Congress' Copyright Office with respect to DMCA exemptions, Stanford law professor, Jennifer Granick, specifically stated that the FCC does not prohibit handset locking.
In the United Kingdom, cellphone network providers don't have to provide unlocking codes at all even after the end of the contract, however most operators offer some form of voluntary unlocking service, depending on the state of the contract and the model of phone. The full Oftel 2002 SIM lock position paper specifies that there is no simlocking law in the UK; the regulator only wants "consumer awareness". The examples within the position paper are just "examples" of current carrier practices for illustration purposes, but do not reflect any official Oftel regulation.
A 2006 study that was sponsored by the Portugal regulator, ANACOM, on handset subsidies and SIM locking concluded that there are no special regulatory concerns on offering subsidized SIM locked equipment in exchange for signing a contract tying a customer to a particular network. Network providers are allowed to apply SIM locks as they see fit, and they may voluntarily remove them if they choose to do so. In the paper, the author stated that the average unlocking fee charged by Portuguese carriers are in the range of 90-100 euros.
In 1998, the Spanish telecom regulator, Comision del Mercado de las Telecommunicaciones, saw that Spanish mobile carriers already provided unlocking codes voluntarily for fee within the first 12 months and for free after 12 months --- so CMT decided not to put any legal framework in Spain. CMT has not revisited this decision since then, therefore there are no simlocking laws in Spain.
Dutch mobile carriers have an agreement with the Netherlands' telecom regulator, Onafhankelijke Post en Telecommunicatie Autoriteit, to establish a code of conduct with respect to simlocking --- specifically unlocking fees can be charged within the first 12 months and simlock cannot last longer than 12 months.
In a 2002 letter to the Dutch Secretary of State of Economic Affairs, OPTA stated that the telecom regulator has decided to start working on the formalization of the voluntary code of conduct into legislation. However, in a 2006 report written by the Dutch Ministry of Economic Affairs, it stated that competition in the Dutch mobile market is sufficient and the formalization of the voluntary code of conduct into legislation is not needed. Thus there are no simlocking laws in the Netherlands.
Many countries listed below have some form of simlocking laws specifying the period of simlocking and the cost of obtaining unlocking codes. However their effectiveness may be questioned when we look at the iphone's worldwide distribution practices.
In France, SIM locks are not prohibited. However, the mobile operator must inform the consumer of the existence of a SIM lock. The subscriber has the right to request that the SIM lock be removed at any time. No later than 6 months prior to the conclusion of the contract, the mobile operator must "systematically and free of charge" provide the subscriber with a procedure to deactivate the SIM lock. Operators may charge a fee for removing the SIM lock prior to the 6-month deadline.
Italy has SIM locking laws that the carriers must specify the amount of subsidies, and subscribers can obtain unlocking codes after 9 months by paying 1/2 of the listed subsidies. The SIM lock must be removed within 18 months.
In Germany, there does not appear to be any effective law regulating SIM locking. For example, the iPhone was initially offered for sale in Germany exclusively through T-Mobile, and it was locked to T-Mobile's network. They began to provide unlocking codes for that phone after they were sued by Vodafone and a temporary injunction was issued requiring T-Mobile to do so. Vodafone's injunction was later overturned, and the iPhone is again available exclusively locked to T-Mobile.
In Hong Kong, carriers are not allowed to SIM lock a phone for the purpose of SOLELY tying customers to their network. But Hong Kong carriers can SIM-lock a phone to protect the handset subsidy or to enforce mobile plan contracts or to protect from theft. After the initial purchase subsidy has been recovered, or the full cost of the equipment has been paid up under a rental or installment agreement, the carrier must provide a detailed procedure for unlocking the equipment free of charge upon request.
In Finland carriers are not allowed to sell simlocked GSM phones, nor are they allowed to offer tie-in sales on GSM equipment. For the purposes of the Finnish law, a tie-in sale is defined as selling the equipment for a discounted price contingent on the consumer also acquiring a new service contract from the seller. Under the terms of a provisional exception, valid from 2006 until 2009, tie-in sales are permitted with 3G handsets, and 3G equipment which is purchased under such tie-in sales may be simlocked. The simlock must be removed free of charge at the conclusion of the tie-in contract, within a maximum duration of 2 years. As of September 2008, the Finnish government is preparing to extend the exception, and at the same time is considering reducing the duration of tie-in contracts to 1 year.
In Australia, carriers can choose whether to SIM/Network Lock handsets or not and usually tend to only SIM/Network lock prepaid handsets. There does not appear to be any regulation or law on simlocking in Australia.
In Canada, the country's only GSM carrier is Rogers/Fido, and they will not provide official support for unlocking their products.
Typically, a locked phone will display a message if a restricted SIM is used, requesting the unlock code.
For example, on the Sony Ericsson T610 mobile phone, "Insert correct SIM card" will appear on the phone's display if the wrong SIM is used. Once a valid unlocking code is entered, the phone will display "Network unlocked". In some cases, the phone will simply display a message explaining that it is locked. This is especially the case with handsets provided by AT&T Mobility.
The code required to remove all SIM locks from a phone is called the master code or network code key.
The algorithms used in earlier Nokia brand phones (based on IMEI and MCC code) have been reverse engineered, stolen or leaked, resulting in many people offering Nokia unlock codes for free or for a fee. Newer Nokia phones have more robust encoding algorithms and permit fewer attempts at unlocking and are not unlockable by these free unlocking programs.
Many other manufacturers have taken a more cautious approach, and embed a random number in the handset's firmware that is only retained by the network on whose behalf the lock was applied. Such phones can often still be unlocked, but need to be connected to special test equipment that will rewrite that part of its firmware where the lock status is kept.
Most phones have security measures built in their software that prevent users from entering the unlock code too many times, usually four. After that the phone becomes "hard-locked" and special unlocking equipment has to be used in order to unlock it.
Handset manufacturers have economic incentives both to strengthen simlock security (which placates network providers and enables exclusivity deals), but also to weaken it (broadening a handset's appeal to customers who are not interested in the service provider that offers it). Also, making it too difficult to unlock a handset makes it less appealing to network service providers that have a legal obligation to provide unlock codes for every handset they've ever sold.
The main reason to unlock a phone is to be able to use it with a different SIM card. For example, when traveling abroad it's usually cheaper to temporarily use a foreign network, for example with a prepaid subscription. Contrary to some beliefs, an unlocked phone can't access extra cell phone towers or give free phone service. All it can do is accept other SIMs.
In some cases, a simlocked handset is sold at a substantially lower price than an unlocked one, because the service provider expects income through its service. A consumer may choose to unlock the phone and continue using his previous provider. Therefore, simlocks are usually employed on cheaper (pay-as-you-go) handsets, while discounts on more expensive handsets require a subscription that provides guaranteed cash flow.
A practice known as "box breaking" is common in the UK and some other markets. This involves purchasing (usually) pay as you go handsets from retail stores, unlocking the phones, and then selling them (often abroad) for a higher price than the subsidised retail price. The SIM card that came with the subsidized handset is then either thrown away or sold or used elsewhere. This practice is entirely legal in the UK, and provides a de-facto limit to the extent to which networks are willing to subsidize pay as you go handsets. In recent times network operators have been insisting that new customers purchase substantial amounts of airtime at the same time as they buy a new handset, in order that the total price they pay comes close to the true value of the handset.
Some companies have begun to offer an e-mail unlocking service. This service requires that the individual who wishes to unlock their phone emails his or hers IMEI number, which is usually displayed by any terminal upon entering *#06#, to the company. The company will then process this IMEI number and email back an unlock code and instructions. Input the unlock code and the phone is unlocked. These email services are usually the most efficient as it is the same method most retail stores will offer.
In 2004, a company BLADOX in the Czech Republic released a small device called a Turbo SIM which contained a small MCU capable of spoofing the network ID during SIM registration. This thin device sits between the SIM card and the phone, in the SIM slot. A small piece of plastic on the SIM is removed to make room for the MCU. The most popular of these devices, originally for the U.S Apple iPhone 3G, is typically called "Universal Sim" after a label printed on the card.
In the Netherlands unlocking is legal provided that the process does not overwrite the handset's flash memory with a (modified) copy of copyrighted firmware, since this would be a breach of copyright retained by the manufacturer. However, unlocking a handset may void its warranty.
In the United States the DMCA formerly was claimed to criminalize unlocking. However, an exemption that took effect 27 November 2006 specifically permits it, and will expire in three years but it can be renewed after that. The exemption only applies to the actual unlocking, not to providing an unlocking device or service, see WIPO Copyright and Performances and Phonograms Treaties Implementation Act.