Nextel Contract Expiration, how to determine?

Hi,

I am trying to determine what the expiration date on my Nextel cellular contract is. I cannot find it on my bill, or logging on to online account management.

I would like to determine this without calling Nextel if possible, as I'm afraid they might pull some trick and extend it if I call.

Any suggestions as to where I can obtain this info?

Thanks,

Steve