Board Thread:Questions and Answers/@comment-37807741-20190111181155/@comment-32182236-20190218021519

It's pretty safe to say Frisk never left the Underground, since Flowey shows up and talks to us. He couldn't have crossed the Barrier.

It's also pretty safe to say they're NOT DEAD, since Flowey shows up and talks to us. That's not possible if we're dead.

It's ALSO pretty safe to say they're not just fine holding their inventory, because otherwise, they'd be able to answer Sans' call, and Sans wouldn't need to resort to leaving a message.

So, three possibilities that I can think of.

1-Frisk attempted to cross the Barrier, but bonked on the Barrier, fell, and woke up after the call was over.

2-Frisk attempted to cross the Barrier, but bonked on the Barrier, fell, and lost their phone.

3-Frisk attempted to cross the Barrier, but got STUCK IN IT.