The term burner, when used in the context of a mobile phone, is typically a pre-paid phone but also one that cannot chew up data fast meaning it's usually a crappy one. (I came across the term from listening to people talking about The Wire, me, being one of the few people who has never actually watched it.)
I saw more than a few people in Vietnam carrying two phones: a burner and a more up to date handset and couldn't really figure out why until I was sitting in the Qantas office in Ho Chi Minh City. That's a whole other story. As I watched someone working two handsets I figured out why: the burner was for making calls and possibly texting while the bigger, better handset was used to surf the web. Free WiFi is prevalent in the country, go figure, so it made sense to keep the base functionality cheap while surfing the data hungry sites and apps for free.
Life hack, anyone?