Although many people use the two terms interchangeably, unlock and jailbreak are two entirely different things, that create two separate conditions for your mobile device.
Examining each one, along with gauging their strengths and weaknesses is the only way to know if one or both of these techniques are right for you.
Jailbreaking and unlocking an iPhone are frequently mixed up with each other. They are completely different from each other. Unlocking an iPhone halts the lock on the SIM card and permits the phone to operate with all carriers, not just the authorized, Apple-licensed carrier. This is what unlocking means. This varies from one country to another country.
Phone unlock is a method that has been around since the creation of the SIM card. A SIM card is a special transferable chip that contains your networks pertinent information.
As a general rule, Network Carriers, such as AT&T, Verizon and Sprint, place a special ‘lock’ on the SIM cards that go into their devices. They do this to ensure that the device in question will only use the network towers provided by the carrier. This of course is expected; the companies only want you to use their towers.
But there are instances where this is a great disadvantage to the user. If the user is out of the country, traveling internationally, most times their devices become useless, unable to transmit data. Also, if the user is in a domestic area where their network is not supported, their coverage will suffer.
Unlock is the process of removing that network lock on the device, effectively allowing it to use any wireless carriers towers. This of course opens up a great deal of freedom to the user, as they no longer have to worry about coverage and where they are traveling.