What makes an alarm path independent?

The value of a second path is that it survives whatever took the first one down. That only holds if the two paths do not share a dependency. Draw the failure scenarios honestly: a shared on-site router or power supply, two mobile connections that both ride the same mast or the same mobile core, or two paths that converge on the same receiving infrastructure. Any of these turns a dual-path design into a single point of failure wearing two coats.

Selectable mobile networks are a good illustration. A communicator that can use several networks is more available than one locked to a single network, but access to several networks is not the same as two independently supervised transmission paths. The question to ask of any signalling product is not how many networks or paths it lists, but which dependencies the paths genuinely do not share.

Real independence is a property you can describe and test: different physical media or radio access, separate power where it matters, and separate supervision so that the loss of one path is detected and reported rather than silently masked by the other. If you cannot say how two paths differ, assume they do not.

Netavo provides alarm signalling with up to four verified paths per site. The paths are Ethernet, Wi-Fi and two mobile SIMs, each of which can itself use more than one network, and each path is verified separately about every 30 seconds, so the loss of any one is detected and reported rather than masked by the others. The unit on site and its power supply are still shared, which is why backup power belongs in the design.