2scents: So, at the end of the day, for the incoming to work properly (718-387-…. and 718-230-….), Hatzalah is relying on Verizon. If Verizon messes up, Hatzalah can only speak to Verizon so they fix it.
BTW, it’s POTS (Plain Old Telephone Service). And VoIP cannot backup an –>INCOMING<– POTS number, unless the POTS provider has a special unusual arrangement.