Should I put my metroPCS 25$ sim card into an unlocked iphone?

I got this metroPCS 25$ plan. They gave me a very bad (unlocked/sim card) phone with a sim card inside it. Second day, i put this sim card into another phone that was unlocked, called it and it worked. I'm planning on buying an unlocked iphone to take out my sim card out of my bad phone and put it inside the iphone. Please tell me if it is gonna work? Will i have problems with metroPCS? Will it work on other unlocked smartphones and so on.

Why iphone won't play media out loud?

I got it used off of a friend but for some reason music, youtube, etc only works with headphones. It wot play out loud or een let me turn up the volume through the side buttons, but it will when headphones are in so i know the buttons arent broken. Any suggestions? Also, the speakers work on calls or for the ringtone.

Selling an iPhone through PayPal?

I listed an iPhone on eBay and the buyer wanted to pay through PayPal so he gave me his email and we spoke through there. He paid me today through PayPal however there was no fees deducted from me… Usually 3.4% but somehow I received the full payment. It seems as though he sent it through the "friends and family" option. Is he unprotected as a buyer? I'm planning on shipping the iPhone to him tomorrow. Am I safe sending it? I know I broke eBay rules. But 10% seller fees is too much tbh.

What's your say in this?

How to find this unknown caller?

This unknown caller called my iphone 5 ios 7 and said your debit card has been hacked (mastercard) and we ask you to reactivate it. First i know its a scam because it wouldn't be unknown or bad customer service if it did happen. Second i'm 13. I don't have a master card or any credit card or or any money its all in my college and only time i get money right now until i'm 16 and get a job is on my bday and christmas. How do i trace this number down. I didn't give it any number cuz i knew right away its a scam