For applications that include universal (also known as global) commands, don’t provide a big list (or even a short one) of universal commands during a call's introduction. These lists fall squarely in the category of stuff callers don’t listen to or remember. In usability testing such a system, the interviewer asked participants what the commands were that they could say. Very few could remember any at all, and nobody was observed using them during the test. We know of no published research on this topic, but logical analysis suggests that no matter how concise you might make this type of message, it will delay the caller from hearing the initial prompt, thus delaying immediate engagement. Instead, present these commands only when callers are more likely to actually need them (e.g., in help messages or in menus offered at task completion points).

See also the section: Commands