When I have my cell phone by my computer?

My comp will start making that weird noise they make when your cell phone is receiving a text.....i don't know how to explain the noise,,,,but you know the one. Sometimes when I'm on my land line home phone... I can hear the same sound in the phone lines when i get a text. Anyway....sometimes when I'm at my computer.....and my cell phone is near it, that noise will happen but then I won't get a text? Why does that happen? Was a text coming in and because my phone was so close to the comp that maybe I lost the text? I have bluetooth but I've never used it....I don't even know what it is. It just seems weird because it seems like its happening more and more....it happens almost every time I'm sitting at my computer.