I am just wondering on the common app when it says:
“If you wish to be contacted via mobile phone, please provide your phone number. Contact methods may include phone calls generated from an automated telephone dialing system or text messaging.”
What is that for? Is that just for them to call you if you get accepted?
Personally, I would rather not get called with my admissions decision. As excited as I am for the colleges I am applying to I plan on not even looking at the decision date in the hopes that one day I will get back my decision. I feel like doing that will be better for my stress levels, and allow me to focus.
So I guess in summary is that phone number used only for admissions decisions? If so then I am probably not going to authorize them.
Also side note does anyone have a link to “etiquette” for answering admissions decision calls? Ex: Am I expected to jump around cheering for the next 5 minutes while the other person is on the line?
Sometimes colleges have a student call you after admissions to answer questions and just make a personal connection. That is most common in my experience. If you end up on a waitlist, they often call when you get off to see if you are still interested. You can always let it roll to voice mail and then decide whether to call back. 
I’d give them a number.
I really wish I had caller id this would be a lot easier if I knew it was them and not some random person. Would they call from the admissions office, or the general school, or is that a wildcard?
You can’t tell. They will leave a message if it rolls to voicemail. You are overthinking. Just put in your number.
My son got calls from almost all the schools he got accepted to but a few days after it was posted online. It was almost always a student calling to congratulate him and answer any questions. He liked it and he’s not big on talking on the phone. They were always very nice and friendly and fine if he didn’t have any questions too.
My son got a call from a student at a school a few days after he submitted his application. It was to invite him to an event at the school next weekend. As intparent said, you are overthinking it and should provide the number. If you check some of the threads of previous years, when kids were wait listed, it seems regional admissions officers were calling to assess whether the student was still interested and these calls were the same day or the day before they were going back to admissions selections. Provide a number you will be checking frequently as, if it comes to a wait list scenario for a school you really are interested in attending, you don’t want to have them move on to someone else because you didn’t provide a phone number.