Do my unused minutes roll over into the next month?

No — minutes don't roll over. At the start of each billing month, your minutes allowance resets to the full amount for your plan, whether you used them all or not.

For example, if you're on the Start plan you get 500 minutes each month. If you only use 200 in a given month, the remaining 300 don't carry over — your next month starts at 500 again.

If you regularly run close to your limit, consider upgrading to a plan with more minutes. See how to change your plan.