What are the hours and when should I call? Microsoft - Product Support operates the call center for this 888-212-3545 MSN phone number 24 hours, 7 days. https://himss.zendesk.com/hc/en-us/community/posts/36979570192275-What-to-do-if-MSN-is-not-syncing-emails-%F0%9D%9F%8F-888-212-3545