Intercom interruptions are a fact of life in a school. Honestly, it's really not as big an interruption as some would make it out to be. There is constant in and out of a school office, with kids coming and going from classroom to office. Our offices have student assistants who run notes and other things to classrooms.
I didn't know you were a teacher. Maybe at your school intercom interruptions aren't that big a deal, but in my classroom, I can tell you that they are. As soon as the intercom comes on, some student turn off or becom so distracted that it takes several minutes to get everyone back on track. In a class period of 45-50 minutes, a couple of intercom interruptions could cut into class time by 5-10 minutes. That's 5-10 of lost learning time. And that is for an average class. If there are several ADHD or other highly distractable students in the class, getting back on track can be very difficult.
Fwiw, we do not have office aides or student assistants to run messages or other things to classrooms.
In my school, intercom disruptions are a big deal. Our intercom clicks when it first goes on. As soon as the kids hear the click, they look up from what they're doing to wait for the message. If the secretary calls asking teachers to send a student down to the office to pick up something that must go home today, all these hands go up. I've already explained to my students that I will never pick someone that raises their hand. I pick someone that was able to ignore the intercom and keep working.
I don't let students go to the office and call for forgotten items. If you forget your homework at home, you miss recess. Most kids don't forget often after that. Forget an instrument at home, you don't get to leave class to go to band that day. Kids need to learn responsibility. If I forget something at home, nobody drops everything and brings me what I need. I deal with it for the day and make sure that the next day I lay whatever it was next to my bag that's going to school.