What, precisely, does "reset network settings" do on an iPhone?

I use "internet sharing" on my Mac, but lately I've been having trouble connecting my iPhone 5 to the resulting WiFi network. I've read advice online to do Settings -> General -> Reset -> Reset Network Settings on the iPhone, but I can only find very vague information on what this actually does. From the name it sounds like a bit of a nuclear option, and before I try it I want to make sure that it's not going to affect my ability to use the cellular network.

So, does the iPhone's "reset network settings" just reset WiFi settings, or does it reset cellular network settings as well? If the latter, is there any danger that this would delete any settings installed by my phone company, causing problems with using internet or telephone services via the 3G or 4G networks?

According to this Apple support page,

This will clear your current cellular and Wi-Fi network settings, including saved networks, Wi-Fi passwords, and VPN settings.

So, it will reset your network connection options, and it will affect internet connectivity, both GSM/GPRS/EDGE/3G/4G and WiFi, but it shouldn't impact "classic" telephone services, because they are usually auto-configured by the carrier and do not require specific settings on the mobile phone.