Why does my iPhone 4 say invalid sim
This usually happens when a hacked/jailbroken phone is upgraded and becomes relocked to the original carrier.
Could it be my sim card?
Could be. Remove it and insert it again.
Here are some troubleshooting tips: iPhone, Troubleshooting authorized unlock issues, http://support.apple.com/kb/TS3198
Last question, is it anyway I can unlock my phone other than jailbreaking it because I don't wanna do that
Authorized unlocks are initiated by your mobile carrier.
See this for a list of carriers that offer unlocking: http://support.apple.com/kb/HT1937
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