With Martin's system, each crewmember gets a cell phone that operates using a prepaid SIM card; they also get a two-week plastic pill organizer filled with 14 SIM cards where the pills should be. Each SIM card, loaded with $50 worth of airtime, is attached to a different phone number and stores all contacts, text messages and call histories associated with that number, like a removable hard drive. This makes a new SIM card effectively a new phone. Every morning, each crewmember swaps out his phone's card for the card in next day's compartment in the pill organizers. After all 14 cards are used, they start over at the first one.