i am thinking about buying an unlocked used iphone off of kijiji & then putting a

koodo phones sim card in it? if i but this iphone how do i know that it wont have problems before i buy it?
also i currently have the keybo from koodo right now, but it snapped in half.. i want an iphone but dont want to pay that big plan i cant afford it, so im buying one off kijiji, then going to koodo and buying a really cheap phone, taking its sim card and putting it into the iphone.

i just have a question though.. does it matter which sim card goes into the iphone.. is it limited to what i can do on it with a certain sim card, or how does that work. because i am not sure which phone to buy from koodo please help
also, when i get this used iphone off kijiji, can i still add apps to it and all that stuff ?
OKAY one more question, i just heard that the sim card im putting into it needs to be "cut into microSIM" for it to work? whats that? is this true or will any sim card work please help

To change simcards in your iPhone you need to take care of two things..one is the sim size and another is whether the phone is unlocked to accept all sim network. Regarding the sim size there are many options like cutting the sim or use the apt sim adapter hardware that is available in the market. If you are going to cut the sim you can get it to a professional or follow the free youtube videos available. To unlock an iPhone the remote unlock service would be a better option because, you need not give your mobile to someone else nor do you have any chance to enter the wrong unlock codes. To get such an unlocking service for your iPhone approach Classicunlocking.com and by submitting the country and network to which the mobile is locked to you will be able to remove the restriction from the respective network. This will be a permanent unlocking solution. Once the iPhone 4 is unlocked you can use it with T-Mobile and keep the contract.