In the study guide, CIPS lists 5 stages of an negotiation:

The opening phase: confirm understanding and get the issues on the table. At this stage, both parties should check agenda, authority and create atmosphere conducive to agreement

The testing phase is an information gathering stage where the hypothesis and assumptions you have made in the planning stage can be tested and confirmed or disconfirmed

The proposing phase: Both sides may start making tentative proposals regarding their offering.

The bargaining phase: Both parties trade concessions; the preliminary stages are over and proposals move from being tentative and general to being more definite and specific.

The agreement and closing phase: both parties should seek agreement or if TOP does not have the final authority, some sort of acknowledgement of what key terms are should be sought.