Why is my iPhone text sound not going off?

I already checked all the settings. Could it be time for an upgrade? Probably so… And yes, its a 3GS i don't need any more crap for having an old phone i'm just using this one because my Mom just got a 5 and I wanted to see how iPhones work before my upgrade in a few months. Why is the sound going off on phone calls but not texts? Also when I go to plug in charger it doesn't make the noise it usually does and it could be because the phone is going. The speaker might be broken maybe? I don't know… Not sure whether to take to Apple Store because I hear they can't really help with 3gs or older model phones or maybe to take to my carrier… Anyone have ATT or know if they are nice about early upgrades? Please specify which iphone you have… Thanks. Please help! My friend who has a 4S was kind enough to help me in the meantime by placing on a loud repetitive vibrate so I don't forget about my texts because the volume is on high and the texts don't go off but the call sounds do? Sad face… Thanks yall

Added (1). Ok… Please give more details.how/why did it break and how did you get it fixed? LOL

The 3GS iPhones break a lot. I have one and just had to get it replaced for many reasons lol. All iPhones are like this. Sure get an iPhone 5 but I gaurantee in maybe 6 months it will start having similar problems! I think they program them that way to make more money.