Using the Commands
270 98-08901C68-O
atd17085763400; //Second VOICE call
OK
CONNECT //Call to 44345678 is being put on hold
//Hang up all calls
atd+44 34 56 78 //DATA call
...
CONNECT //Move to online Data state
+++ //ESC sequence ==> back to command state
ath
NO CARRIER
OK //Data call terminated
at+fclass=1
OK
atd+44 34 56 78 //FAX call
...
NO CARRIER //Fax call was terminated by remote side
atd035659260,345,22; //VOICE call with tones sent after connecting
OK
CONNECT
3 4 5 //Sent as DTMF tones
... //Pause
2 2 //Sent as DTMF tones
//Voice call is hung up
atd0356592,60 //DATA/FAX call with comma
//Comma is ignored; 035659260 is dialed
CONNECT