Under this system, drivers respond to calls for service put out by dispatchers - if they wish.

Paid drivers cared for the fire station and responded to all fires.

After the driver responds, it says in a friendly voice, "Pretty good, just half a tone too low."

Five of the deaths occurred after the drivers responded to calls made to their offices, the police said.

The taxi followed, the driver responding to a quiet order from the man in back.

The driver had responded instantly to the voice of the man beside him.

The other driver responded with a gesture and motioned for him to pull over.

The driver responded, "It must feel so good to be taken care of and protected like you are."

When the driver didn't respond, she punched her foot on the accelerator.

The drivers respond by going on high alert for malfeasance.