Question: In a UMTS network using AMR or AMR2 codec types, what is the status of TX SCR (Source Controlled Rate) operation on the User Equipment (UE) side?
Option 1: TX SCR operation is disabled by default but can be enabled by the network.
Option 2: TX SCR operation is dynamically switched based on the VAD (Voice Activity Detection) flag.
Option 3: TX SCR operation is always enabled.
Option 4: TX SCR operation depends on the type of speech frame (e.g., SPEECH_GOOD, SID_FIRST).
Explanation: According to specifications for UMTS AMR and UMTS AMR2 codec types, TX SCR operation is consistently set to an enabled state on the User Equipment (UE) side, utilizing source-controlled rate handling for efficient bandwidth usage based on speech activity detection.