In Sophie Kinsella's book "I've Got Your Number," the protagonist reflects on her choices regarding mobile phones. She questions why she didn't purchase a new phone sooner and contemplates the practicality of always carrying a backup device, likening it to the necessity of having a spare tire for a car. These thoughts highlight the importance of being prepared for unexpected situations in modern life.

This humorous observation encapsulates the character's feelings of frustration and urgency in a tech-dependent world. It emphasizes how essential communication devices have become, suggesting that having a spare phone should be just as habitual as ensuring that one’s vehicle is ready for the road.