Which means this command: set audio aec enable?

AEC is not an abbreviation for a codec-enabling function; codec selection is handled by separate configuration commands unrelated to echo processing.

AEC stands for Acoustic Echo Cancellation, a DSP-based feature that detects and removes echo caused by audio feedback between the speaker and microphone. Enabling this command ensures that far-end participants do not hear their own voice reflected back, improving call audio quality.

Noise cancellation is a distinct audio feature typically controlled by a separate command (such as a noise reduction or NR setting), not by the AEC parameter.

Bandwidth economy or call economy settings are controlled through codec or quality-of-service commands and have no relation to the AEC audio processing feature.