These numbers are dedicated to providing Enterprise support for both QuickBooks Online and QuickBooks Desktop users. The support team is available during the following hours:
QuickBooks Online Enterprise Core: Monday to Friday, 6 AM to 6 PM PT +1-888-283-2036
QuickBooks Online Enterprise Premium and Elite: 24/7, any time, any day (except for closed holidays)

https://support.okta.com/help/s/question/0d54z0000afocqpcqz/does-quickbooks-have-247-hour-service-call-quickbooks-support?language=en_us