Delayed Delivery of Voice Messages

Hi all. One of our employees is not receiving his phone call messages. He just checked his phone and just received messages left yesterday. We have checked the settings on the phone and it is not set to delay delivery. Since this is a business phone and we need to receive the messages in a timely manner, would anyone have any suggestions to fix this? Nextel says they don't know what it could be. Help!!

Thanks.

That is the main reason I left Nextel over a year ago.
I suggest a Sprint Hybrid