How would you do that? How can you prevent anyone from knowing you layoff 300 person until you contacted all 300 persons? They tried to contact him and failed.

How would you do that? How can you prevent anyone from knowing you layoff 300 person until you contacted all 300 persons? They tried to contact him and failed. Should they wait until they reach him before contacting all other employees? What if he was number 100 on the call list? Do they tell the 99 others to please not say anything for a few days and ask for a media embargo because they couldn't contact Joe? What if he was on vacation? Should they wait until 100% of employees are not sick/away/in vacation and postpone the announcement a few weeks? (Weeks? I'm being generous here).