Drupal Online Ticket Response System(OTRS) | drupal.org : This modules allows the integration of OTRS 2.0+ (Online Ticket Response System) with Drupal to provide a mechanism for organizations to track the detection, reporting, and resolutions of problems/issues.
OTRS is an Open source Ticket Request System (also well known as trouble ticket system) with many features to manage customer telephone calls and e-mails. The system is built to allow your support, sales, pre-sales, billing, internal IT, helpdesk, etc. department to react quickly to inbound inquiries. You can find out more here: http://www.otrs.org/
Module features:
Requirements:
Functional installation of OTRS 2.0+ (does not need to reside on the same server)