Question: In an IMS network, when an I-CSCF receives a Request-URI with a SIP representation of an E.164 number, what action does it take prior to performing an HSS Location Query?
Option 1: The I-CSCF directly queries the HSS using the original SIP URI.
Option 2: The I-CSCF translates the SIP URI into a Tel URI format for the query.
Option 3: The I-CSCF routes the request to the S-CSCF for further resolution.
Option 4: The I-CSCF invokes ENUM/DNS translation mechanisms without altering the URI format.
Explanation: Before conducting an HSS Location Query, the I-CSCF must translate a SIP URI representing a telephone number (E.164) into the Tel URI format. This step is crucial for ensuring compatibility and effective querying of the HSS.