The present document specifies the Single Wire Protocol (SWP). SWP is the interface between the UICC and the CLF. The present document defines: ? Layer 1: The physical layer which is responsible for activating@ maintaining and deactivating the physical link between the UICC and the CLF. It defines electrical (voltage and current levels@ timing and coding of voltage and current levels)@ mechanical (physical contacts) and functional (data rates) specifications. It also defines the initial communication establishment and the end of the connection. ? Layer 2: The data link layer which is responsible for the physical addressing of the data through frames and Link Protocol Data Units (LPDU). The data link layer is also responsible for error notification@ ordered delivery of frames and flow control. This layer can be split into two sub-layers: - The Medium Access Control (MAC) layer which manages frames. - The Logical Link Control layer which manages LPDUs and is responsible for the error-free exchange of data between nodes. Three different Logical Link Control layers are defined in the present document.