Question: In UTRAN's Iu interface utilizing ATM transport, what protocol is employed for dynamically setting up AAL-2 connections towards the Circuit Switched (CS) domain, building upon an earlier version with added capabilities?
Option 1: Q.2630.1 without modifications
Option 2: Q.2630.3 as a replacement for earlier versions
Option 3: SSCOP (Service Specific Connection Oriented Protocol)
Option 4: Q.2630.2, adding optional capabilities to Q.2630.1
Explanation: The correct answer is Q.2630.2 because it specifically adds new optional capabilities to its predecessor, Q.2630.1, for the dynamic setup of AAL-2 connections over Iu towards the CS domain in UTRAN's ATM transport option.