LetterAgent
Mail physical letters by just asking your AI assistant.
Super G3 is an extension of the Group 3 fax standard (ITU-T T.30 Annex F) that lets two fax machines converse at up to 33.6 kbps instead of the usual 14.4 kbps, so a typical page moves in about three seconds. It is a speed feature, not a separate fax technology, and both machines must support it: otherwise they quietly fall back to standard G3 speed.
| Standard G3 | Super G3 | |
|---|---|---|
| Standard | ITU-T T.30 | T.30 Annex F |
| Modem scheme | V.17 (14.4 kbps) | V.34 (33.6 kbps) |
| Time per page | Well under a minute, often half that | A few seconds |
| Added compression | MH / MR | MMR and JBIG options |
| Needs both ends to match? | No, it is the universal baseline | Yes, or speed falls back to G3 |
Group 3 is the fax standard almost every machine made since the early 1980s follows. The "super" part layers on the V.34 modem scheme, the same modulation trick that made 33.6k dial-up modems fast. V.34 probes the phone line first and picks the fastest rate the line can hold, so a clean line gets the full 33.6 kbps and a noisy one steps down. Annex F also added smarter compression, including JBIG, which squeezes the white space out of text pages harder than the older schemes.
One detail worth knowing: Super G3 is backwards compatible by design. A Super G3 machine talking to an old Group 3 machine negotiates downward automatically, so nothing breaks; you just do not get the speed.
Not in a way you would notice on a text page. The higher speed and better compression mostly mean the page arrives sooner and with fewer transmission errors on long documents. Fine detail on dense pages can actually look slightly crisper because the JBIG compression handles patterns better than the old run-length schemes, but resolution stays where it was: the standard "fine" mode is the same dots per inch either way.
This is where the story changes. Super G3's V.34 modem scheme was built for analog phone lines, and VoIP compresses audio in ways that corrupt modem tones. Faxing over VoIP therefore uses T.38, a protocol that carries the fax data as packets instead of modem audio, and most modern Super G3 machines support T.38 alongside V.34. The speed advantage still roughly holds over T.38, but the exact rate is negotiated by the gateway equipment, not the machines.
Practical upshot: if you are buying a machine for a VoIP line, the "Super G3" badge matters less than the "T.38 support" line in the specs.
Online fax skips the modem entirely. The document travels over the internet as data and converts to a fax signal only at the carrier's end, using T.38 or a gateway. LetterAgent works the same way: you describe the fax to your AI assistant, approve the exact quoted price after the page count is verified, and pay once. Recipients must have US or Canadian fax numbers, and fax is available in testing while activation is in progress, so it is described as in testing rather than promised to send immediately.
Ready to fax it? Fax with LetterAgent: describe it to your AI assistant, approve the exact quoted price, and it is sent.
LetterAgent is a working name. Prices include print, postage, and our service fee. US prices in USD, Canadian prices in CAD (Canadian prices exclude applicable sales tax, added at checkout). Currently in private testing.
Need help? Ask your assistant: it can check a job's status any time. If it ever can't handle something: hello@getletteragent.com