Standard Support is included with all Sitecore Maintenance Agreements and includes:
Standard Support offers a target response time that varies from one to three business days depending on the severity of the problem reported via the Sitecore Support Portal.
24/7 Premium Support is an optional upgrade that provides 24/7/365 telephone “hotline” support for business-critical issues. Designed to help customers maximize uptime, the response time for critical issues is reduced to one hour, 24 hours a day, 7 days a week. 24/7 Premium Support customers also enjoy enhanced response times for non-critical support issues.