It's not - it's actually a rectangle, with one corner cut off to prevent it being inserted into the phone incorrectly. It's called 'polarizing'.
no
yes
you have to put YOUR sim card in. from your old phone.
Contact your cell phone provider.
The LG Prada is an unlocked phone. The phone is a SIM card phone capable of being on any carrier that accepts SIM cards. Currently (2012) T-Mobile and AT&T are SIM card carriers.
Only if your texts are saved to the phone and not to the sim card.
yes?
The SIM card is what goes in the back of some cell-phones to both make them work and also carry the information chip needed like for a pre-paid phone card for example. A dual SIM cell-phone would carry 2 SIM cards in this instance.
It depends on the phone and carrier.
You can not use a sim card in another cell phone carriers phone. They can only be used for the same carrier.
Any cell phone that is unlocked requires a SIM card to work. If you own a Sidekick cell phone that is unlocked you are able to use a carrier other than T-Mobile. For this reason, it will require a SIM card to work.
If your cell phone has a sim card, your phone may say out of service if you are far from a town or city. A phone needs a cell tower to work, so you may get an out of service message if you are not close to cell tower.