Review your payroll withholding. When you get your lump sum it will be taxed at that rate.
Any ESP stock that haven’t vested, they will refund you that money.
They will pay out any unused PTO, but be sure to check and know how much time is due to you.
The outplacement company they will make you aware of is cr-p. Mostly useless.
But do sign up as TMO is paying them.
If you are remote, they will hold the severance check until they get back all equipment, company ID/swipe card and P Card if you have one.
After your last day, your next phone bill will reflect consumer pricing for what you have now.
Research and make changes if needed.