I have a texting question

Hi there. I do not have an iPhone. I have a run of the mill Android type phone. My question is this. Is there an iPad app that will let me text using my existing phone number then obviously receive the replies? My phone is not very good, and I'd like to be able to text using my iPad or iPod Touch. I've tried other apps before, but the problem is they give me a new phone number which is a hassle for everyone I'm texting to.

Thank you
Paul