switel M 820 Mode D'emploi page 111

4. If the SOS number can't be connected, the phone will dial next SOS
number until the call be answered. If no SOS number answers, the
phone will continue dialing the SOS number one by one until the call
connected.
5. The SOS operation can be cancelled by pressing the End key.
Tips for SOS Dialing
SOS Numbers available
Automatic jump to SOS Key menu to set SOS Number
3 seconds warning tone. In case of unintentional SOS
dialing, press the End key to cancel the call.
Send a message to all preset SOS Number
Dial SOS numbers one by one no matter the SOS message is
sent successfully or not.
Answered
Turned into handsfree mode
Press and hold SOS for 3s
Dial out until the call connected
13
No SOS Numbers
No answer