Could expand the phone's purpose by adding random job related events sent via text messages to your phone.
Completing those events rewards you with extra Ecash (30-50 or something).
A car that needs to be towed away because of an accident (mechanic)
One of the buses needs a cleaning because of a passenger having thrown up/dropping food/etc (public driver)
You have to pick up weapons/vehicles/drugs/etc and deliver it to the mafia boss (criminal)
I'm out of ideas for the other jobs haha, would love to see what you guys think.