As well as making it possible for a consumer the ability to consider several networks, there's a number of other reasons why you might like to network unlock your mobile phone before the end of your contract. For those who are heading to foreign countries as an example, you may choose to work with a local SIM-card when you're there to stay away from high roaming rates. Possibly you've decided to sell your phone then you'll probably get more money and more interest in a mobile that is free to work with with just about any carrier.
Absolutely nothing is illegal about unlocking your mobile. It is yours and you are clearly within your legal rights to use it on any network you would like. However, there's a good chance that carrier unlocking your mobile phone may end your warranty, so it may be best to hold off until you've finished your contract before you decide to leave your current carrier.
A few carriers won't chargeyou for unlocking guidance while others can easily charge about $70. It is also worth bearing in mind that each networks has unique policies connected to how long you might have had your regular monthly or sim only agreement for and how to get your code. Nearly all carriers have online forms to submit a SIM unlocking request, but quite a few will need you to phone their helplines. How long it may take to unlock your cell phone yet again ranges widely between each network. In the UK, EE for example, will unlock an iPhone in 7 days, while Plusnet declare it might take up to 15 calendar days to unlock IMEI locked devices.
If you are uncertain which website you can trust, I highly recommend Unlock.Zone. They offer unlocks for all major brands and networks, provide a guaranteed price match promise, plus most significantly, offer a 100% refund policy in the unlikely event they cannot unlock your cellphone. I've used them personally and was really happy with the service I received and ultimately that they successfully unlocked my smartphone.
Here's a link to their home page: Cellphones Unlock