Question: What is the specific Domain Name used in the host part of a SIP URI to indicate confidentiality protection of MC Services identities in 3GPP networks?
Option 1: mc-secure.3gpp.org
Option 2: mission-critical.3gppnetwork.net
Option 3: encrypted-mc.3gpp.net
Option 4: mc1-encrypted.3gppnetwork.org
Explanation: The correct Domain Name, as per the specified telecom standard for indicating confidentiality protection of MC (Mission Critical) Services identities within a SIP URI's host part, is indeed `mc1-encrypted.3gppnetwork.org`. This specific string is utilized to signify that the user part of the SIP URI contains protected identities for services like MCPTT (Push To Talk), MCData, and MCVideo, each constructed according to their respective 3GPP protocol specifications.