I use Asterisk 16.5. Also i use this option.
rtptimeout = 10
This option work correct when call is not holded. Asterisk terminate call after 11 seconds if no RTP or RTCP activity on the audio channel.
But when sip client holds the call this option is not works correctly. And Asterisk dos not terminate call after 11 seconds if no RTP or RTCP activity on the audio channel.