[Newbie question] Stereo recording from phone line-in

[dwrae]

First of all, phones do not have a line in. They only have a mono mic input.
For proper line level recording, you need a USB audio interface. The cheapest are devices like a Behringer UC222 (without input gain control), but please have a look at other ones from Behringer, Steinberg, Lexicon, Alesis, etc.