Send a voice memo by passing audio: true to sendFile(): 
await space.sendFile({
  path: "/path/to/note.m4a",
  name: "note.m4a",
  audio: true,
});
Voice notes appear as playable audio bubbles on iMessage. Other providers may treat audio as a generic file attachment — branch on space.platform when the UX matters.

​
WhatsApp Business audio

On WhatsApp Business, send audio through the Cloud API builder: 
import { wa } from "skyline-ts";

await space.send(
  wa.audio({
    link: "https://cdn.example.com/voice.ogg",
  })
);
Cold outreach still requires an approved template — see Markdown.