It doesn’t matter. Look at a pursuit scenario. Agency A is chasing suspect vehicle, Agency B responds without letting either their agency or Agency A know they are coming, and Agency A’s unit and B’s unit collide because they don’t know the other is there. Also, if I am a Boss and responsible to know where my cops are and what they are doing, somebody better let me know they are leaving their post and why, especially if they are leaving their jurisdiction. Because when something happens and I’m sitting in front of IAB, I better have a damn well good answer. It’s basic Academy stuff.
Someone has to let the math Lt or the dispatcher know where they are. you don’t respond and cut yourself off from back-up or delay their response.