Unfortunately, WAN Failover is not what I need because it works only in case WAN + mobile but I am using only mobile to send SMS notifications (without APN) and single WAN.
I looked at Reporting Configuration for Networks events to FTP/Email but in my case, it can't send notification without connection with any email server.
Ping Reboot with SMS notification seems that not works when WAN is not connected. It is strange and in my opinion, it should send a notification in the same situation as the timeout at ping.
Update: It seems that Ping Reboot not works for remote addresses. Am I sure or something I set wrong?