Reporting a student who cheats Firstly, I do not believe this to be a duplicate of the related recently posted question due to the key fact that that user was anonymous to his class and I am not. 

This has happened 3 times now. While taking standardized tests, someone cheats. These aren't just classroom tests, but rather officially proctored, nation-wide tests. The first time, some students had significantly more time, both starting before the official call to start, and ending after the official end. The Proctor was pretty relaxed, and either didn't notice / didn't care. The second time, someone's phone went off twice, and on full volume (the student in question had to stand up and manually turn the phone off). The Proctor did not alert his superiors, although many students had lost a significant amount of time and the incident negatively impacted our scores. We were told beforehand that any distractions during would be an immediate invalidation of the test (we even had to keep our phones in a box), but this seemed to go unnoticed. The third time was similar. 

I complained to my peers afterward, and they all told me not to tell anyone or do anything for fear that it would cancel or negatively impact our scores (most of them did well). I didn't feel comfortable with this, but I didn't report anything both for fear of both my reputation being impacted, and for fear of my scores being cancelled on a test that I studied significantly for and potentially did well on. If I were to report any of these incidents, most people would immediately know that it was me who had filed the report, and I would be severely socially ostracised. I did/do not desire this at all. In hindsight, I should have kept it to myself, not expressed my worries to my friends / acquaintances, but unfortunately this did not happen. 

In a situation like this, what is the appropriate course of action post-disclosure? Report the student in question and risk negative reputation, a cancellation of scores, and hard work put in (but do the right thing and have fairness reign), or keep the cheating to oneself (and preserve reputation but carry a dishonest weight)?
I don't know in which country you live. If a phone ring, this is not cheating because a phone that rings does not provide any information to a student. However, if a student is using his phone to look up at information on the internet, take phone calls or send messages, or look at answers stored on his phone, this is of course cheating. So if the phone just rings, I don't think that it really matters.

About ending after the official end, if it is just a few minutes, maybe that the professor just decided to give a few more minutes to give a chance to those who could not finish the exam on time. I don't know about your country, but in my native country (Canada), it is not something unusual that a professor will give 5 more minutes to students if he sees that many of them have not finished the exam. In that case, this would not be called cheating, as long as every student can have this extra time.

So, if you think that it is cheating, then you can report it (if you think you are OK with the possible consequences). But from your description, I am not sure that we can really call this cheating.