Using 2 tty, if we send the ATH on USB3, the CONNECT will be received on USB0 :(
But we could see some interresting notifications.

bertrand@bertrand-Latitude-E5410:ofono (master *%)$ sudo ./gatchat/cdmadial --control /dev/ttyUSB0 --modem /dev/ttyUSB3
Control: /dev/ttyUSB0
Modem: /dev/ttyUSB3
APN: (null)
CID: 0
Control: > ATE0Q0V1\r
Control: < \r\nOK\r\n
Control: > AT+CFUN?\r
Control: < \r\n+CFUN: 1\r\n\r\nOK\r\n
Current modem mode is 1
Modem: > ATD#777\r
Control: < \r\nCONNECT 3100000\r\n
Modem: < \r\n^DATACON:1\r\n\r\n^DSDORMANT:0\r\n
Modem: < \r\n^DSDORMANT:1\r\n
Modem: < \r\n^HRSSILVL:80\r\n
Modem: < \r\n^HRSSILVL:60\r\n
Modem: < \r\n^HRSSILVL:40\r\n
Modem: < \r\n^HRSSILVL:20\r\n
Modem: < \r\n^HRSSILVL:40\r\n
Modem: < \r\n^HRSSILVL:60\r\n
Modem: < \r\n^HRSSILVL:40\r\n