Question: In an IP Multimedia Subsystem (IMS), what is the primary purpose of the procedures outlined for codec and media characteristics flow negotiations in a multi-media session?
Option 1: To establish a new resources reservation for every media flow modification.
Option 2: To prioritize media flows based on Quality of Service (QoS) requirements.
Option 3: To determine and negotiate the set of media characteristics (including codecs) between endpoints, both initially and during session modifications.
Option 4: To allocate fixed bandwidth for all potential future media flows at the outset of a session.
Explanation: The correct answer, Option 3, aligns with the described procedures' goal of negotiating media characteristics (including common codecs) between endpoints. This is crucial for both the initial setup and any subsequent modifications to a multi-media session, ensuring compatibility and optimal resource utilization without necessarily requiring new resource reservations for every change (as implied in Option 1). Options 2 and 4 are not directly related to the primary purpose of these negotiation procedures.