[Hilo] How to use command of <AT+CVHU>?

[Hilo] How to use command of <AT+CVHU>? What’s the behavior when I use it?

Answer: <AT+ CVHU> is used for hand up control for only VOICE call. It has impact on the behavior of ATH and DTR. For example:

AT+CVHU=0 (“Drop DTR” ignored, ATH disconnects)
OK
ATD10086;
OK
Drop DTR ---- But it is ignored, call is still ongoing
ATH —The call is disconnected
OK
AT+CLCC
OK

AT+CVHU=1 (“Drop DTR” and ATH ignored)
OK
ATD10086;
OK
AT+CLCC
+CLCC: 1,0,0,0,0
OK
ATH —It is ignored, call is still ongoing.
OK
Drop DTR---- DTR is ignored, call is still ongoing
AT+CLCC
+CLCC: 1,0,0,0,0
OK
----Wait the other side to disconnect the call

AT+CVHU=2 (“Drop DTR” behavior according to &D setting. ATH disconnects)
OK
ATD10086;
OK
AT&D0
OK
Drop DTR----DTR is ignored, call is still ongoing
AT&D1
OK
Drop DTR----DTR is ignored, call is still ongoing
AT&D2
OK
Drop DTR----“Drop DTR” disconnect the call, then “NO CARRIER” returned
NO CARRIER