Bring your phone to court with you. And, if possible, the papers from your phone bill (especially documents that came with the phone).
Petit larceny is a misdemeanor.
Clark County, NV practitioner.
Petit Larceny is a misdemeanor. However, if the prosecution proves that you knew the phone was stolen, they can charge you with Concealing Stolen Property, which is a felony. Nevertheless, it sounds like an honest mistake that will easily be dismissed. Bring your phone and your phone bill showing that you accidentally picked up the wrong phone. Unless there is some other evidence showing that you intentionally took the persons's phone, it should be an easy dismissal.