Question: In a GERAN Iu mode of operation for speech teleservices, which statement about supported codecs is INCORRECT regarding User Equipment (UE) and Network responsibilities?
Option 1: UE must support Narrow Band AMR codec family (Full Rate AMR and Half Rate AMR) but not necessarily EFR.
Option 2: Network must support both AMR and EFR codecs simultaneously.
Option 3: UE shall support Enhanced Full Rate (EFR) or Wideband Adaptive Multirate (AMR-WB) speech codecs.
Option 4: Network is only required to support at least one of either the AMR or the EFR codec, not necessarily both.
Explanation: According to specifications for GERAN Iu mode, the network is given flexibility, being required to support **at least** one of either the AMR or the EFR codec, not necessarily both. Thus, stating that the network **must support both AMR and EFR codecs simultaneously** is incorrect.