How do you unlock a phone to all sim cards?

It depends on what brand and generation of phone you have. But as a general rule, you will need an unlocker device, usually USB based, but older ones uses parallel ports, and service cables. For newer generation nokias, it is far more challenging to unlock, that it requires replacement of some phone electronic components. For old phones, most of which are no longer marketed, you can open it using codes. But you will need to know to which network it was locked.

How do you unlock a phone to all sim cards?
In the Philippines it's easy, all you have to do is go to one of the cellphone stores in Greenhills Shopping Center and they will unlock it for you for US$ 1-2.
Reply:You usually have to pay someone to do it. The machines that do it cost hundreds or thousands of dollars.





Some places require you to send the phone in while others will send you the unlock codes via text message or can even unlock it remotely.





It costs around $50 to have it done, but will drastically raise the chance of selling your phone at a decent price when you're done with it.





Try doing a search for "model### unlock" on yahoo or google (I prefer google for tech. stuff, but it's your call).
Reply:If your in your contract past 6 months, you can ask your phone carrier to unlock your phone. Tell them you wish to go to Asia and use a local GSM Simm card. I was told this worked for some people. I have 3 phones and 2 were not locked when I bought them.