I dont know where to insert sim card in lg vu cu92...

if you are trying to use the phone with a sim card that you dont usually use with that phone it is most likely locked to another phone take it to your service provider and ask them to unlock it to use on your lg vu . If its your regular sim card then sim card reader is malfunctioning . you will need to have it fixed

you can check it with other sim card ,if it remains the same problem ,it may be locked to particular network wont accept any sim card other than the particular network ,you can unlock it and used to other network,try here http://www.theunlockspot.com/lg-vu-cu920/rs10wp9/

it sounds like you locked your sim card out of your phone, i recommend getting a new at&t sim card and that should fix the problem

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.

actually if you are going to use att's prepaid service, you can just insert that sim card in your lg vu.

Try cleaning the contacts on the sim card. if that doesn't work go into the phone store and ask for a replacement sim.

Be sure that the sim card is in correctly. I had the same problem and then I noticed the small outlined picture of the sim card in the back of the phone. The whole time I was inserting the sim card the wrong way.

Make sure you insert it the right way. Dont assume it will not fit if it is not inserted correctly.

Hello,
Pull the battery out of the phone and underneath is where you insert the sim card.

After you take your battery out, take your sim card out and under where the sim card there is a slot for the memory card. Hopes this helps.