> ## Documentation Index
> Fetch the complete documentation index at: https://faxbeep.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Glossary

> Terms used in these docs: TSID, CSID, station ID, I-Fax and scan to email.

## CSID

Called Subscriber Identification. The ID of the machine that **receives** a fax. When it answers a call, it sends this ID to the machine that calls, as the fax standard ITU-T T.30 says. It is usually the fax number of the machine that receives.

The CSID is not the ID of the sender. Faxbeep does not show a CSID. For the ID of the sender, see [TSID](#tsid).

## I-Fax

Internet Fax. A copier mode that scans a page and sends it as an email, with the page attached, usually as a TIFF file. It uses your network and your outgoing mail server, not a phone line. The standard for it is ITU-T T.37.

The name of the mode depends on the maker: look for "Internet Fax", "I-Fax" or "iFax". An online fax service is not I-Fax: it sends a normal fax, so test it with a test number. See [Internet Fax test](/tests/internet-fax).

## Scan to email

A printer or copier function that scans a page and sends it as an attachment to an email address. See [Scan to email test](/tests/scan-to-email).

## Station ID

The setting on a fax machine that holds its own fax number, and often a name. The machine sends this ID as its [TSID](#tsid). Many machines also print it at the top of each page they send. Some machines call this setting the fax header.

Faxbeep does not mask the ID that your machine prints on the page, because it is part of the page image.

## TSID

Transmitting Subscriber Identification. The ID of the machine that **sends** a fax, as the fax standard ITU-T T.30 says. It is usually the fax number of the sender, or a short name.

When your machine sends a TSID, Faxbeep shows it as the sender of your fax. A number shows with its middle digits masked. When it sends none, Faxbeep shows "Unknown". See [How the sender shows](/results/sender).


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