Whats unlocking?

Hi.

What do you mean by unlocking phones?
What does it do and does it usually cost money or something?

1. Lock phone to SIM card. If your phone has simlock to the SIM you cannot use any other SIM than the one you have: SIM broken makes phone useless. A simlock is a lock programmed into a mobile phone which only allows one company's SIM to be used in the phone. The reasoning behind this is to keep your custom to that network. Simlock is also referred to as SP Locks or Network locks. Once your simlock is removed you can place any (dependent on phone model) SIM card into it including foreign networks if you take the phone abroad.

2. Lock phone to Operator (Network or Service Provider). If your phone has simlock to an operator, you can use any SIM from this operator in your phone. You can switch between contract and prepaid as you wish, but not to a different operator.

3. Lock phone to CODE (Product Lock or Offer Lock). If your phone has simlock to a code, the phone checks a special "password" (GID) on the SIM that must match your phone. Providers often use different passwords for contract and prepaid.

So unlocking is: Removing simlock on the phone so you can use the phone with any compatible SIM Card. Unlocking will allow you to use other service providers' SIM card. For example if you have an ABC GSM phone you can only put in an ABC SIM card, but if you unlock you can put in DEF XYZ, etc.

in other words unlocking is put your phone free for another´s sim cards of others operators bye stay cool

if you go to an operator to unlock your phone of course you gonna pay to unlock to another operator. "we"nokia lover´s try to put a simple idea if you pay the equipment so you can choose wath operator to use today and another day other one do you understand and maintaines the same equipment/mobilephone.you can choose wath you want to do with your phone because its yours.
if you want to unlock your phone you have lots of sites in the net who gives you to download software to the respective phones and sites to buy the cables to proceed the unlucking of your phone , today exist ´s another services of unlocking , we call remoting unlocking , that means unlock your phone by code
stay cool best reggards

Thanks for the info.

What about when i put another sim in a phone and it asks for the Security or puk code? Does "unlocking" remove that?

depends if is the securaty code you have one option by via cable and soft you can see the pin that you have put into the phone and changed it for the universal nokia pin 12345 or another one .
by via remoting unlock code you cannot i think ..
if is the puk the puk is a number of the card you cannot change this number because is a number of the sim card ok stay cool bye friend

Ok. If i want my phone unlocked, what do i need to do and what happens? Do i get an unlock code, type it into the phone and im done? or does it come from sms, cables etc?

hy depends , if your mobilephone is a dtc3 such as 8210/5210/3310 etc...you will need an flasher cable and software , o you can use too an mbus cable and mbus soft like for example eppromm tool or a box in this kind of phones only connect the cable to your computer and to the phone into the pinouts then start the software click unlock and its done .
if is a dtc4 phone like 3510/7650/8310/6310/etc... you can unlock by flasher cable too but the best way is by remoting code just put your phone imei , phone model and mobile operator that your phone is locked just put a post into the forum unlock codes (dtc4 only) and waith for someone give you the code that its like this example : #pw+1234567890+7# just insert thiss code into the phone and its unlocked . ok stay cool