Ness is the brand most people use. If you have a monitored alarm, it will go to a control room. Control room will act on your preset conditions i.e. alarm fires, they will call you and tell you if somebody is in the house or not, then ask what you want to do, if the duress/panic fires they'll send a patrol. They don't automatically call the police from the control room.
That said most of the burgs I know of late have had alarms and the offenders don't care. They go through the front door and look for keys/cash/computers and are out and gone in under 5-10 mins with the alarm still sounding.
As for cameras, offenders wear hoodies/caps so footage is not as useful. More useful for checking for odd cars in the street etc. leading up to the burg.
As for home invasion, that's a totally different story. Make sure your physical security is strong, have an exit strategy depending on where they're entering from, keep your keys/wallet/phone including spare hidden or close to you so you can grab on exit. Don't engage as you have no idea how many are waiting outside. Sh!t can be replaced lives can't. Also have a remote duress button on your keys you can hit if required. Our alarm is wireless on/off and the key fob has a panic button.