Under the ECPA, an electronic communication includes any type of communication transmitted by some electronic means, unless it involves the transmission, at least in part, of a human voice, which would then be a wire communication. Such a definition of electronic communication encompasses written messages, documents, and photographs transmitted by telegraph and facsimile-type communications services. It also includes terminal-to-terminal computer messages and numerically coded messages transmitted to digital display paging devices. The ECPA specifies six types of communications not requiring a wiretap-type order for interception. They are publicly accessible radio communications, tracking devices, the radio portion of cordless telephones, tone-only paging devices, and pen registers and trap and trace devices.