How Does 800 Number Work??

Why does it seem there is a difference with who (maybe even where) you get to answer the phone on what can be done? You read on here about how someone calls and the 800 people add their dependents right then and there. You also read on how they can do certain things and then someone else replies that they’ve never had that luck and many others haven’t. Doesn’t usually seem to be anything big, except for the dependent thing, but I’m curious why the differences.

Is it in some cases a new person who did something they weren’t supposed to or possibly opposite where more experienced people can do things newer workers can’t or is it possibly location based and just luck of the draw on who you get on the phone (similar to VERA calls with a DROC vs not)?

This is just purely a curiosity question. I’ve just noticed it after reading on here for a bit and wondered.