The worldwide dial plan proposed by the International Telecommunication Union recommendation E.164 reserves multiple country codes for future use. These unused codes present an opportunity for a potential covert channel over the public switched telephone network utilizing a spoofed source phone number of a call to send information to a mobile device. The reserved country codes can act as a delimiter indicating that a secret message is being sent. By spoofing a call using a reserved country code number, the application listening on the mobile device will be able to intercept the call and extract information from the remaining digits based on ASCII encoding in a decimal format. The purpose of using a reserved country code number is so that there will be no denied service to the user with a call from a legitimate phone number.

Date of creation, presentation, or exhibit



Originally presented at the 10th Annual Symposium on Information Assurance (ASIA '15) June 2-3, Albany NY

Document Type

Conference Paper

Department, Program, or Center

Department of Computing Security (GCCIS)


RIT – Main Campus