Instead of thinking "She just has hand over her ear"
someone though "Some block has invented time machine in the future and the first person he send back into the time was his mom who always loved Charlie Chaplin's movies, so now he could finally bring that girl from IT over (yes, he lives with his mom, as do most of the people who believe this story) + he had to invent phone which could transverse time, because his mom would not just go without being able to call him every 3 hours"