We're still piecing together what caused Verizon's extended service blackout, but network experts point to possibilities based on how it transpired.

Verizon says a software problem caused the glitch and it is conducting a postmortem, but experts say outages are "a fact of life" these days.

A major service outage affecting Verizon customers that has lasted for hours and prevented some local 911 calls from going through continued Wednesday evening -- but there is no evidence of a cyberattack,

During the Verizon outage, police warned that contacting 911 could be tricky. Big disruptions can have cascading effects on everyday life.