Android Phone cannot send, receive calls or texts?

My phone was working fine this morning. I could receive, call and everything. Now when I try it automatically hangs up (and goes to the lock screen), wont send texts and refuses to get anything.
I have checked my service on the Straight Talk official website. It says my service is fine and I have no overdue balance.
I've called customer service and they weren't really all that helpful.
Beyond that did a factory reset to my phone, still didn't help.
My phone is a Samsung Galaxy Ace and I have no availability to the SIM card to take it out and put it back in. (Unless you know where and how I can do this please let me know.)
It seems so sudden it did this when everything was working absolutely fine earlier.
Please help!

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