I am trying to put my boost mobile sim card in my att phone and it keeps asking for an unlock code how will i find out what the code is

No. ATT uses GSM while Boost Mobile uses CDMA and TDMA.

You can, however, use it with T-Mobile or Straighttalk as long as you get the Network Unlock Code for the phone. Without the code, the phone will be locked to the ATT network only. You can either pay a website to get you the code, or if you have had the phone long enough you can call ATT tech support and request the code from them for free.

you actually need to unlock your phone to use the simcard not just a code. boost mobile and tmobile run and different networks to its not as simple as putting in a different sim card.

Yes it should if the LG mobile phone is unlocked. If not, when you insert the Boost SIM card in the LG it will ask for a Secutity Code.
If the SIM card won't work in the LG, please get back to me.

if you want to use your phone on a service like t-mobile or cingular, it wont work, you can only unlock it for iden, like boost mobile, nextel.
you can unlock it your self by going here
http://multiplexelectronics.home.att.net/software.html

you can unlock it to use a boost mobile sim card by going here
http://multiplexelectronics.home.att.net/icunlock.html

try unlock codes from http://www.unlock-free.com/ and http://www.mobile-unlocker.com/

most probably you have not switch on the wireless mode. make sure you have wireless mode ON. than it will ask you for network code. than you can enter the code. or also make sure you are putting sim card in correct direction.

sorry but you can try online , unlockitnow.com , mobile2mobile.net or a mobile center

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Hope These Works