At Noibu, billing is based on session consumption. For each term, your company will define a session commitment, and the term's pricing is calculated by multiplying the session commitment by a set rate. However, if you exceed your session allowance, contact your Noibu CSM for a set of Buffer Sessions. Buffer Sessions are a small allowance of extra, free sessions to give you some wiggle room to accommodate the growth of your business. Typically, the amount of Buffer Sessions allowed is around 5% of the term's committed sessions.
If your company has Buffer Sessions enabled, the allowance will appear in the Session Consumption charts on the Billing page in the Company module.