Looks like there is a good answer here already. Just confirming that there are a few things which play into the response time and whether or not a call will occur, and the response expectation will be determined by how you have your service set up.
As the other poster mentioned, Dialer Delay, which is a setting controlled on your panel, and the time it takes for you to disarm will be the biggest influences on response. Read about these features at the above links.
In addition, Two Way Voice will delay phone calls if enabled, and if you enable the Text Chat feature in system manager this will also add a delay, allowing you time to interact with the text chat and confirm or disregard through that feature.