CSID (Called Subscriber Identification)
Definition
The configurable name string transmitted by a fax machine during session setup and printed in the fax header bar on the received document; may be set by the sender and is not inherently trustworthy as authentication.
- Full name
- Called Subscriber Identification
- Transmitted during
- Fax session setup
- Appears in
- Fax header bar on the received document
- Reliability
- Sender-configurable, not inherently trustworthy
Common questions
Why can't the CSID header be treated as proof of who sent a fax?+
The string is simply a name the sending machine is configured to transmit, set by whoever has access to the device's settings. It is not tied to a verified phone line or identity the way caller ID on a phone call can sometimes be cross-checked, so it can be changed to show any name.
What should an examiner rely on instead of the CSID header to verify a fax's origin?+
Cross-referencing the transmitting line number captured in call logs from the telecom carrier, along with metadata in the fax protocol itself where available, gives a more reliable trail than the printed header text alone.
Related terms
- Copy Generation
- The number of copying steps between the original document and the copy under examination; each generation introduces resolution loss, noise amplification, and...
- Fax Header Bar
- The line of text printed at the top of each received fax page under regulatory requirements (US FCC 47 CFR 68.318, UK...
- FTIR (Fourier Transform Infrared Spectroscopy)
- A vibrational spectroscopy technique used in toner analysis to identify the polymer backbone and functional group composition of toner binder material; ATR...
- Ghost Image
- A faint background impression of a previously copied document visible in a later photocopy, arising from incomplete cleaning of residual toner from...
- MMR Compression (Modified Modified READ)
- An ITU-T fax compression standard (T.6) used in high-quality fax transmission modes; produces characteristic compression artefacts visible in fine character strokes of...
- Platen Glass
- The flat transparent surface on which original documents are placed for scanning in a photocopier or flatbed scanner; contamination or scratches on...
- Polyester Toner
- A toner binder formulation based on polyester resin, dominant in office photocopiers and laser printers from the 2000s onward; characterised by FTIR...
- SEM-EDX
- Scanning electron microscopy with energy-dispersive X-ray spectroscopy. The electron beam excites characteristic X-rays from each element present in the target grain, giving...
- Trash Mark
- An extraneous mark appearing at a consistent position or periodic interval in photocopied documents, arising from platen glass contamination (fixed position) or...