Resume Screening: Initial review of the candidate's resume to assess qualifications and experience.

Recruiter Call: A phone call with a recruiter to discuss the candidate's background, interests, and the role.

Technical Screen: A technical interview, often conducted over the phone or via video call, where candidates solve coding problems and discuss their approach.

On-site Interviews: A series of in-depth technical interviews at a Microsoft office (or virtually). These interviews focus on coding, system design, problem-solving, and sometimes domain-specific knowledge.

Behavioral Interview: Questions about past experiences, teamwork, leadership, and how the candidate handles various work situations.

Final Round: A final interview with a hiring manager or senior leader to assess overall fit for the team and company culture.

Offer: If successful, the candidate receives an offer and discusses compensation, benefits, and other details.

Describe how you would design a scalable and efficient system to handle real-time chat messaging for a global user base. Include considerations for both backend infrastructure and frontend user experience.