When a viewer tunes to a channel, the receiving hardware sends a request to the CAM. In the case of OSCam, this request includes the SRVID. Without a mapping file, the OSCam log files and web interface would display only a raw hexadecimal number (e.g., 0x1339 ), making debugging and monitoring difficult for the administrator.

: In an Oscam setup, the server can distribute channel information, including SRVIDs, to connected clients. This allows multiple devices to access the same channel lineup and subscription information.

In the MPEG-2 and DVB standards, a Transport Stream (TS) contains multiple elementary streams (video, audio, data). These are grouped into "services." A Service ID is a 16-bit number (ranging from 0x0000 to 0xFFFF) that uniquely identifies a service within a specific Transport Stream.