'I' grade calls are calls where "the immediate presence of a police officer will have a significant impact on the outcome of an incident". This is typically categorised as where there is, or is likely to be, a danger to life, a serious threat of violence, serious damage to property or serious injury. The response time to a call of this urgency is 15 minutes.
'S' grade calls are calls where there is a "degree of importance or urgency associated with the initial police action, but an emergency response is not required". The response time to a call of this urgency is 60 minutes.
'E' grade calls are calls where police attendance is required, but an emergency police response is not. The response time to a call of this urgency is 48 hours.
'R' grade calls are calls where police attendance is not required. This typically means that the caller has been dealt with appropriately by the call handler.