Ques: What are Definitions of L1 L2 L3 Support
Level I Support - Telephone help desk or answer center support. This support typically includes individuals that are trained on the product, but may have limited experience. They should be able to resolve between 50% and 75% of all issues. Level II Support - Experienced professionals, or professionals that know something specific about the client's implementation or business.
Second line are (typically) internal teams out of datacenter, basic services like database teams, administrational teams, customizing or integration teams of your organization. They are more specialized. People working here typically should be involved in problem management.
Level III Support - Technical experts who would be employed to resolve issues that are typically very difficult or subtle. This may be software developers or programmers, systems engineers, or other technical professionals that are generally not required to solve "routine" issues not involving product defects, conflicts, or data damage.