Question: In 3GPP's Generic Bootstrapping Architecture (GBA), what is the primary purpose of using GBA_Digest with SIP Digest credentials, especially in environments without a UICC or SIM card?
Option 1: To enhance voice call security for subscribers.
Option 2: To provide a more secure access method to applications than password-based HTTP Digest.
Option 3: To facilitate faster data transfer rates for IP-based services.
Option 4: To simplify the authentication process for IoT devices.
Explanation: GBA_Digest, utilizing SIP Digest credentials, is specified to offer enhanced security for accessing applications in scenarios where traditional security elements like UICC or SIM cards are not available. This method surpasses the security provided by basic password-based HTTP Digest (as per RFC 7235 and RFC 7616) without additional enhancements, thereby ensuring a more secure authentication process for subscribers in such environments.