Not sure about other services' protocols but in the last couple if months mine had started doing 'general broadcasts' for A calls in the hope that if theres a crew closer than the response being sent they can offer themselves up. These general broadcasts used to be very rare and used as a last resort, but we were averaging 4 an hour the other day usually the transmission finished with "currently no resources to send". That same day i went to a call for an MI and as i walked through the door the man took his last agonal breath and promptly arrested on me. I got an output back after each shock but even after full ALS he died at hospital. It took us 30 minutes to reach the man as we were the nearest resource due to nearer crews being tied up elsewhere. Im convinced a quicker response to this would have had a better outcome. I really felt sorry for the wife and community responder who were on scene helpless to do anything. At the hospital i spoke to a crew who just before the time the call came to us, cut short their stand down to respond to chest pains which turned out to be a cold.