Board Thread:General Discussion/@comment-28962359-20160825041654/@comment-27701762-20160825144139

A possibility that I think is more likely is that Frisk is trapped somewhere, whether it is in the Barrier, or in the Underground in a place that can't be reached, or in some pocket dimension created by Photoshop Flowey. It explains why the call doesn't get through and goes to a message, and why Flowey is still able to talk to Frisk (since he talks about "your friends," i.e. Frisk's friends). Especially since some amount of time has passed since the defeat of Photoshop Flowey (Toriel needs to return to the throne and institute a new rule about humans and make people feel a bit better about living in the Underground, or there needs to be enough time for Undyne to stage a revolution and Toriel goes back, and Sans & Papyrus make regular visits to her in the Ruins). Being specifically dead wouldn't make much sense in the chain of events.