I would like to know how to alert the admins if the internet circuit goes down. A client has a single internet feed. It has a SIEM to send email alerts to the admins on servers, network and security incidents. They have rules on their outlook to forward certain critical events to their personal email accounts, which pop up on their phones. The question arose as to how they would be alerted if the circuit itself went down.
I'm looking for a working example with the right tools in an economical fashion. Really dating myself, but I have worked with an AS5300 with a SIM bank in the past, but I'm really looking for a scaled down solution. Back then, someone I know had a phone connected via a serial interface into his monitoring server. His piece of code would use the phone to text alerts out.