When a child is registered, heaven and earth is moved to get information and you would NOT BELIEVE how many parents don't care to provide it, or provide non-working phone numbers, etc. Only family member is contacted unless there is secondary contact authorized by family. CPC or SP are not technically "family" and would not be contacted unless DT specifically authorized in writing at some time that they had access to information or to the child on the school grounds. Rules are strict about who has access to picking up children, etc. It's all about confidentiality and protection.
As far as ISS, I read somewhere that Somer was kept back for a while - maybe that was wrong info. A lot of parents won't let teachers use ISS because they don't want to come and pick the kid(s) up. As far as fights, they happen every day, kids swatting other kids, tripping, etc. Only if it was an ongoing disruptive problem that generally put the other kid(s) at risk - or, or course, if the other child was hurt - would the teacher necessarily do ISS. Unbelievably, teachers are hardly allowed to give out ANY punishments in today's system and if they do, they have to write it up and send out warnings to parents, etc. before actually going through with it. Then the teachers are called on the carpet for not having "control of the classroom".
Then there is OSS (out of school suspension) where the child is kept out of school for a day or more. Parents REALLY HATE THIS ONE. It means they have to make arrangements for the child to be watched. Most don't - they just let the kid stay home. No big deal.
I dare anyone to spend ONE day in a classroom with 30 kids and come out sane. Try volunteering at a school. It's a real eye-opener.