Question: What is the primary condition for the 'Attempted outgoing preparation inter-RAT handovers with Iur-g interface (UMTS->GSM)' measurement to be valid in a telecommunications network?
Option 1: The handover must be for packet switched traffic.
Option 2: The RNC and CN must be from different vendors.
Option 3: The handover is specifically for circuit switched (CS) domain traffic from UMTS to GSM.
Option 4: The measurement only counts successful handovers.
Explanation: This measurement is specifically valid for circuit switched (CS) domain handovers, highlighting the nuance between CS and PS domains in telecom networks. The correct answer points towards the measurement's applicability to circuit switched traffic from UMTS to GSM.