Errors

Every rejected promise and every error event carries a PhoneError; match it with instanceof:

class PhoneError extends Error {
  code: string;        // match on this
  requestId?: string;  // give it to support
  param?: string;      // offending field, for API errors
}

code is one of the API error codes, or one of these, specific to the browser:

Code	Cause	What to do
`microphone_denied`	The user or the browser refused microphone access	Explain how to allow it in the browser settings
`microphone_not_found`	No microphone, or the chosen one was unplugged (mid-call too: then sent as an `error` event and the call is muted)	Ask the user to plug one in or pick another
`speaker_not_found`	The chosen speaker is unplugged, or the browser did not allow it	Pick another one, or leave the default
`audio_unavailable`	The page cannot run Web Audio or reach media devices (old browser, insecure origin)	Serve the page over HTTPS, update the browser
`user_gesture_required`	`call()`, `answer()` or `testMicrophone()` ran outside a user action, or the browser blocked the sound	Call them from a click handler
`not_supported`	An `output` was set in a browser that cannot choose the speaker	Hide the speaker picker when `phone.canChooseOutput` is false
`ephemeral_key_failed`	`getEphemeralKey` threw or did not return the JSON of `POST /v1/ephemeral-keys`	Check your server route
`connection_lost`	The WebRTC session could not be restored for 2 minutes (network down, UDP and TURN blocked)	Show it, offer to retry with `phone.connect()`

Two API codes also come from the SDK itself: line_offline when you call while the phone is not connected, and invalid_request with param: 'lineId' when call() cannot pick a line. Anything unexpected is internal.