Asterisk Call Duration

Hi I’m new to asterisk. I was able to install asterisk 1.4 on Cento 5.1 with freepbx. I have this situation which I want to accomplish. I want to implement a call duration on incoming calls. For example they want to call an extension in my office I want it limited to 10 mins only. The scenario is like this friends of my employees will call asterisk and an IVR prompt will answer asking for an extension number. They will enter the extension number and there phone conversation will be limited to 10 mins. Is this possible? If yes can anyone please give me a headstart. Any help will be appreciated. Thank you in advance!!