Question: For IMS terminals supporting audio, what is the requirement for supporting encoding by a particular audio codec if the terminal already supports decoding by that codec?
Option 1: The terminal must also support encoding by that codec to ensure symmetric communication.
Option 2: There is no requirement for the terminal to support encoding by that codec; decoding support is sufficient.
Option 3: The terminal should support encoding but only for specific scenarios marked in green in the codec selection test results.
Option 4: Encoding support is mandatory only for Enhanced aacPlus, not for Extended AMR-WB.
Explanation: According to the specifications for IMS terminals supporting audio, there is no stipulation that a terminal capable of decoding by one of the specified codecs must also support encoding by that codec. This flexibility allows for varied implementation strategies based on terminal design and intended use cases, emphasizing decoding capability as the primary requirement.