Does the iPhone allow Circuit Switched Data dial-up? I know CSD (Circuit Switched Data) is a really old technology and going to be obsolete. I just want to know: Does iPhone allow CSD dial-up like old mobile phones (without Jailbreaking it)? 

If the answer is Yes, how do I configure it?
In theory (totally theoretical) the iPhone does support CSD on the tech sheets, but you'd need your network provider to provision it onto your phone, and there's no apps in the app store that would allow you to do it due to the hardware access it'd need. 

You could probably do it, but you'd need some jailbreak software and matching hardware which if you've got an engineering background wouldn't be impossible, but merely a pain in the backside.