When a Plivo call dies at answer time, check the hangup code before touching your code. A 7011 means your answer URL never produced a usable response, so debug reachability and status codes. An 8011 means it answered with something that is not Plivo XML, so debug the response body. Treating one as the other sends you down the wrong half of the problem.

Context: Plivo's own audio-streaming skill reference documents the hangup-code distinction agents must not guess at: 7011 means Plivo never got a usable HTTP response from your answer URL (bad status, timeout, empty body), while 8011 means it got a response whose body was not a Plivo XML document. The reference warns not to name a code the evidence does not pick: read the status line first, then the body.