Please explain the use of this flag in the HMP .config file

SetParm=0x0705,0 ! SD_ParmDtmfTalkOffFlag (0=Disable anti-talkoff,1=Enable)on sigDet

There is no documentation on this that I can find. What does it do?

Is this flag active when HMP is configured for a SIP trunk and to receive RFC2833 DTMF events?