When people say a phone is “unlocked,” what do they mean?

Question by Jenifer: When people say a phone is “unlocked,” what do they mean?
There are so many advertisements for “unlocked” phones, and I’m kind of confused as to what it means. I guessed it meant you could use one provider’s cell phones on another provider’s network, but then how do you get the features? For example, if you unlocked an iPhone and put it on another network, the apps still wouldn’t work, would they?

Best answer:

Answer by 2Negative
Depends on the app but from what I hear most apps work fine when going from AT&T to T-Mobile. But T-mobile sales the I-phone in other countries so they already know how to set it up.

What do you think? Answer below!


  1. A SIM lock, simlock, network lock or subsidy lock is a capability built into 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 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.

    Most mobile phones can be unlocked 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.

  2. If a phone is unlocked it can be activated on any carrier that uses the same signal format. (CDMA vs. TDMA vs GSM. Ask your carrier for more details, and for what type of signal format they use.) Whether the features can be used or not depends on whether your chosen carrier supports them/

  3. A locked phone will accept only the sim of a particular network provider. This phone should not accept sim provided by any other provider and would show invalid sim!! But when unlocked, it should work with all of its own features and accept services provided by any network company.

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