I have a Cingular cell phone with a text messaging package. How can I check the number of texts I have left?

I have a texting package with AT&T (formerly Cingular). I used to be able to check how many texts I had left for that month on my cell phone, but I stopped using the texting feature for a while and now that I'm using it again, I've forgotten how to check those monthly texts. I looked on their website, but I don't see any info about this. Hoping someone here knows! Thanks!