On January 5, 2015, DJI launched 24/7 tech support for Inspire 1 customers via email or live chat. Telephone support remains a business hours option only.
For live chat and email inquiries, DJI says it will respond to tech support requests within one hour. The support page states that DJI is evaluating the service extension to other product lines, such as the popular Phantom series of quadcopters.
More details and contact info here on the DJI Inspire 1 support page.