Does AT&T Provide a Joining Bonus

I've an offer from AT&T but my joining wouldn't be anytime before the date mentioned on the offer. However, for joining AT&T, I'll have to return my Joining Bonus and some certification fees that my previous company paid for me. Do you think I could ask AT&T to pay me a heft bonus (Around 3-4L) considering my loss, and also considering that I've another higher paying offer from another company ?