A prepaid mobile phone also known as prepaid wireless, or Prepay, and even as disposable phone, is a mobile phone for which credit is purchased in advance of service use. The purchased credit is used to pay for mobile phone services at the point the service is accessed or consumed. If there is no available credit then access to the requested service is denied by the mobile phone network.
Prepaid mobile phones are heavily used in the Bourne franchise by agents and other characters to avoid been tracked or followed by the surveillance systems and goverment agencies.
Bourne, knowing Simon Ross is been watched and heared by the C.I.A. squad in New York, carefully drops a prepaid phone in Ross' pocket to contact him without been listened by the C.I.A.