What would make a cell phone suddenly stop sending and recieving text messages?

Got this phone from “Straight Talk” that is doing this, or actually, not doing this and I’m paying for the texts by the month. The device is under warrantee and they’ve sent me a prepaid package to sent it back to them first. Then they send a new one (hopefully not a recon) with all my contacts intact and activated. I use this for my job so I’ll be going dark for that time and am considering blowing off the texting just to keep going. Is this phone likely to have more trouble if the texting is out? It’s a 100 dollar phone and I’ve had it less than a year (Samsung SCH451C). The amount of money I stand to lose would be more than the phone is worth.