Question: What is a key requirement for deploying an IP Multimedia Subsystem (IMS) in a fixed-mobile convergence scenario?
Option 1: Separate S-CSCFs must be used for fixed and mobile subscribers to ensure authentication scheme compatibility.
Option 2: At least one S-CSCF should be capable of serving both fixed and mobile subscribers simultaneously.
Option 3: All fixed subscribers must authenticate using a different scheme than mobile subscribers.
Option 4: Fixed-mobile convergence is only possible with an additional, dedicated authentication server.
Explanation: This option aligns with the requirement to ensure seamless coexistence of authentication schemes for both fixed and mobile subscribers within the same network infrastructure. By allowing at least one S-CSCF to serve both types of subscribers, it facilitates a unified approach to managing sessions and security, which is crucial in a converged environment.