My buddy just told me he found out that his cell phone is being answered from 2 different towers. Is it possible that someone could obtain some type of spy software to access his calls??? Any private eyes out there or knowledgalbe folks???? thanks.

Yes, there is mobile spy software.
But the mobile cell phone spy only works on part of the phones.
You need to check whether it is compatible to your phone here:
Mobile Spy Software - Spy on Mobile Phones
Features:
Text Message Monitoring
Records every SMS message sent or received.
Sender’s Number
Recipient’s Number
SMS Date / Time
Message Text
Call Monitoring
Logs all inbound and outbound phone calls.
Number Dialed
Number of Caller
Call Date / Time
Call Direction

There is even mobile spy software which can record calls voices like this one:
FlexiSPY iPhone/Symbian/Windows Mobile/Blackberry Spyphone - Mobile Spy Phone Spy Software