If the phone is not answered in 7/8 rings it automatically goes into the voice mail mode to keep a message from the caller. How to prevent it from going into that mode and to retrieve the call so that one is able to talk to the caller directly?

To have the voicemail option disabled for a particular extension, kindly log a call at the IT Service Desk by calling extension 2121 or sending an email to [email protected] with that request.
The voicemail option would then be disabled from the system for that particular extension.