Sim Lock and unlocking

A SIM lock, Simlock or Network 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:
Countries (the phone will work in one country, but not another)
Network/Service providers (e.g. AT&T Mobility, T-Mobile, Vodafone, etc.)
SIM types (i.e. only specific SIM cards can be used with the phone).

In some 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 in Australia for example you have a Vodafone or Telstra branded phone, it displays the relevant logo and may only support features provided by that network (i.e. 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 02 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.



Types of SIM locks

The country lock only allows the use of the phone with SIM cards that originated in a specific country or group of countries.

A network lock only allows the use of the phone with SIM cards that belong to a specific network.

The most common lock is the service provider lock (SP-lock). Many different service providers may use the same physical network (e.g. MVNOs). An SP-lock ensures that the handset is only used with SIM cards for the same service provider that marketed the handset. Service providers sometimes substantially subsidize handsets, and locking the handset improves the odds that its use will economically benefit the service provider.

The most restrictive type of lock which can be used is the full SIM card lock, which means that a phone will only work with one SIM card. If that SIM card malfunctions or is damaged, the phone will no longer work and must be serviced.

Some carriers may have separate locks for the different countries they operate in, so that a phone purchased in America may not work with a carrier's British counterpart or vice-versa.


Laws On SIM/Network Locking

In many countries, locking a handset is legal and may even be required. Some providers never unlock handsets, even after a customer has fulfilled their service contract.[citation needed]

On the other hand, SIM locking has countercompetitive effects on the cellphone service market. In some countries, this is considered sufficiently undesirable to warrant regulation or prohibition of the practice. Belgium is the only European country that outright forbids simlocking and contract/phone bundling. However, the iPhone's launch in Europe has illustrated that none of the current regulations in place amount to much consumer protection.

In the United States, the two national GSM carriers, T-Mobile [1] and AT&T Mobility[citations needed] will unlock your handset if you have an active account in good standing for at least 90 days. This is a change in practice, as before merging with Cingular, AT&T Wireless was known for never unlocking handsets. The US does NOT have any simlocking regulations --- and American GSM carriers are still providing unlocking codes for free.

In the United Kingdom, cellphone network providers don't have to provide unlocking codes at all even after the end of the contract --- see O2's position of not providing unlocking codes for the iphone at the end of the contract. The alternative to an unlocked handset is a sim free mobile phone. A sim free mobile phone is a phone that comes unlocked and is not branded on any network such as Vodafone, O2, Orange etc. [1]

In France, the simlocking laws were bypassed by Apple with an insane unlocked iphone price.

In Germany, T-Mobile only "promised" to provide unlocking codes for the iphone --- only after they were being sued by Vodafone in the injunction case. Notice that Vodafone's injunction was later overturned --- thus meaning that there is no effective simlocking laws in Germany.

In The Netherlands and Spain, providers must provide unlocking codes, but can charge a fee for this during the first 12 months after purchase.

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.[2] It basically means that Hong Kong carriers can simlock by just giving some vaguely defined reason.

In Finland carriers are not allowed to sell simlocked GSM phones, but they can simlock 3G handsets.

In Australia, carriers can choose whether to SIM/Network Lock handsets or not and usually tend to only SIM/Network lock prepaid handsets --- thus there is no regulation or law on simlocking in Australia.


Unlocking technology

A handset can be unlocked by entering a special code, or in some cases, over-the-air by the carrier.

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 unlock code is verified by the phone itself, and is either stored in a database or calculated using an obscure mathematical formula by the provider.

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 its 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.

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Unlocking via code

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 (you can find this by pressing *#06# on your phone) to the company. The company will then process this IMEI number and email back an unlock code and instructions. Input the unlock code and your phone is unlocked. These email services are usually the most efficient as it is the same method most retail stores will offer.


Unlocking via mail

Some companies have begun to offer a "mail-in" service. These services allow the user to send their phone in and have it sent back in an unlocked condition. The benefit to this is that the user doesn't have to become a "cell-phone technician" and also comes with the assurance of a money back guarantee.[3]

Regulations on unlocking

Unlocking a phone without the permission or unlocking code from the provider is usually in breach of the agreement with the provider, though most countries do not make specific laws prohibiting the removal of SIM locks. (In many markets, it is also unlikely that a customer would prematurely unlock a pay-as-you-go phone over the counter, since they are not legally bound by any such contract anyway).[citation needed] For example, in Poland, the law states that providers cannot word their customer contracts so that they forbid the removal of SIM locks, and the process is entirely legal providing that the IMEI number of the phone is not changed during the unlocking process.[citation needed]

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.[4] 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.

Locking in WWANs

Many operators provide HSPA services for laptops and the devices they sell are not SIM-locked, but the software drivers provided with the device are locked to a specific network operator only. Examples include Vodafone[citation needed] in Greece and Wind Hellas[citation needed]. It is possible for end users to flash the devices with the manufacturer's original firmware, or use another set of drivers, or a different operating system (eg Debian GNU/Linux) which does not have these restrictions. For example, the Huawei E220 sold by Vodafone is SIM-unlocked but has the VMCLite software which can only operate on Vodafone networks, but the user can download the Huawei's original software (called Mobile Partner and indicated as UTPC) and flash the device, or use a non-Windows OS or third-party software