He uses a 'laptop' for business when he travels.
(..) - Rachel is not a name. - Then what is it? John, on the luggage, there's a label. E-mail address. Er, jenny.pink@mephone.org.uk. She didn't have a laptop, which means she did her business on her phone. So it's a smartphone, it's e-mail enabled. So there was a website for her account. (..)2010 TvShow: Sherlock Title: A Study in Pink Season: 1 Episode 1