You should never hear the numerical codes on the radio if the agency is using it as intended, but tons of places do voice them. The "9 echo 1" should be voiced as "cardiac arrest" (with "ineffective breathing" if subtype 1 is the one chosen, but that's kind of redundant).
There is also Emergency Fire Dispatch now which also has response levels including Echo. An Echo call for both EFD and EMD indicates immediate threat to life.