Question: In an IP Multimedia Subsystem (IMS), what is the typical number of Serving-Call Session Control Functions (S-CSCFs) involved in a basic IMS session between two User Equipments (UEs)?
Option 1: One S-CSCF for both UEs
Option 2: Two S-CSCFs, one for each UE's network but shared for the session
Option 3: Two separate S-CSCFs, one dedicated to each UE
Option 4: The number of S-CSCFs is determined by the type of media being transferred
Explanation: In IMS, each User Equipment (UE) typically has its own Serving-Call Session Control Function (S-CSCF) for handling sessions. When two UEs engage in a basic IMS session, each UE's S-CSCF is involved, thus requiring two separate S-CSCFs - one dedicated to managing the session for each UE. This ensures efficient call setup, management, and teardown processes tailored to each user's network context.