At any given time, up to two crews can be signed up in EMS Manager to receive calls. The first crew, called the primary or duty crew, takes most calls that are dispatched. This includes all medical calls or lift assists, all motor vehicle accidents, certain MABAS or Mutual Aid requests1, and any fire calls that are located in the city. If the duty crew is staging on a fire call, without patient contact, and another medical call is paged, then the Incident Commander should release the duty crew to respond to the new call. A second crew should respond to the fire call to stage if needed.

The second truck crew, or secondary crew, will respond if there is a second call while the duty crew is at the first call, or if there is a fire call out in the country, a MABAS or Mutual Aid for an ambulance to stand-by or stage1, to a city fire call if another call is paged and the duty crew leaves the fire scene, or to a motor vehicle accident2.

1For all MABAS or Mutual Aid requests, the duty does not go UNLESS for an active transport or for a Life Safety Box.  In all other cases (such as for a fire call or standby at the station), the second truck crew should respond.
2The second truck responds to motor vehicle collisions non-emergent unless upgraded by the IC or the primary ambulance.