what the carrier is saying in this case is...

here is a 183, bring up media... BUT

here is a REASON ( with q850 most probably )

you can conditionally hangup now..

EG.  183 with Q850 code 1 ( Unallocated number )

now if you dont hangup, the carrier plays a recorded announcement saying "unallocated number"

key here is, you can decide if you want the recording, or to just hangup when you get the reason.