Wait. Your question is a little vague. Are you trying to get one mailbox to notify at more than one phone, or more than one mailbox to notify one phone.
If it's the latter, then ctelguy may have your answer.
If the former, then it depends on the model of vm you're using. If you've got a flash vm, then no. If it's a NAM, then it's dependant on the sw revision you're running. If it's a call pilot, then yes.