Question: What is the format of the Conference Factory URI in a SIP-based IMS network?
Option 1: It takes the form of an HTTP URI with a host portion set to the visited network domain name.
Option 2: It takes the form of a TEL URI with a host portion set to the home network domain name.
Option 3: It takes the form of a SIP URI with a host portion set to the home network domain name prefixed with "conf-factory.".
Option 4: It takes the form of an SMTP URI with a host portion set to the serving network domain name.
Explanation: The Conference Factory URI is used in IMS networks for conference-related operations. As per the specifications, it should be in the format of a SIP URI, which is widely used in IMS networks for signaling and session management purposes. The host portion being set to the home network domain name prefixed with "conf-factory." ensures that the URI is unique and can be correctly routed within the network.