Increased pressure and ticking clocks, failures and mistakes, duty and responsibility, loss of control

A phone breaking
Leaving the phone somewhere
The phone being stolen
A teenager's phone being confiscated as a consequence
Being without a phone while it's being repaired
Partially breaking a phone and being unable to replace it; having to use it though certain important features don't work

Being bored (while standing in line, at a red light, etc.)
Not being able to call or text others when away from home
Having to recreate the information on one's phone because it wasn't backed up properly
Not having immediate access to emails, voicemail, and texts
Getting lost without the phone's GPS
Missing an appointment because the character can't access their calendar
Missing out on impromptu get-togethers that are set up via text message
Losing meaningful pictures that had not yet been backed up
Needing to replace the phone but not being able to afford it, meaning the character has to go without for much longer