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Mostly yes. A USB fax modem with current vendor drivers still works with Windows Fax and Scan, but two things have changed: you need a real analog phone line, and a January 2026 Windows 11 update (KB5074109) removed four legacy in-box modem drivers, which broke older soft modems that depended on them. If your modem stopped working after that update, this is probably why.
KB5074109, released January 13, 2026, took four driver files out of the Windows 11 image: agrsm64.sys, agrsm.sys, smserl64.sys, and smserial.sys. These were legacy soft-modem drivers dating back decades, and Microsoft removed them because of unpatched security vulnerabilities in the kernel-level code. Microsoft's note was blunt: modem hardware dependent on those specific drivers would no longer work. The removal was intentional, not a bug, and there is no official fix beyond replacing the hardware.
| Situation | What happens |
|---|---|
| Old internal soft modem using the removed drivers | Stops working after KB5074109; no driver update will restore it |
| USB fax modem with its own vendor driver | Still works; the removed files were never involved |
| USB modem that relied on the in-box drivers | Stops working; check the vendor for an updated driver or replace it |
| Windows Fax and Scan itself | Still ships with Windows; it just needs a working modem underneath |
The modem is only one third of the setup. You also need a driver that Windows accepts and, crucially, an analog phone line. The modem plugs into a real wall jack, not into a VoIP adapter or a digital office phone system, which mangle fax tones often enough to make sending unreliable. If your home or office has gone all-digital, the modem has nothing clean to dial through, and no driver update will fix that.
Controller-based USB modems (ones with real fax hardware inside, like the long-running USRobotics 5637) are the safest buy: they carry their own processing and do not lean on the in-box soft-modem drivers Microsoft keeps pruning. Cheap no-name USB modems are more likely to be soft modems that depend on exactly the kind of driver Microsoft just removed.
Open Device Manager, find the modem, and look at its driver details. If the driver list includes agrsm64.sys or smserial.sys (or their 32-bit siblings), that modem is dead on a patched Windows 11 machine. If it lists a vendor-supplied driver from USRobotics, Zoom, or another modem maker, it should still be fine. And if the modem shows a yellow warning triangle after the update, the driver it wanted is simply gone.
Honestly, only in narrow cases: you have an analog line, you fax rarely, and you want no subscription. For everyone else the math has shifted. The modem, the line, the driver maintenance, and the Windows update lottery are a lot of moving parts for a device that sends a few pages a month. An online fax service moves all of that to someone else's infrastructure.
LetterAgent takes the same approach. You describe the fax to your AI assistant, approve the exact quoted price, and it is sent to US and Canadian fax numbers, no modem or phone line on your end. Fax is currently available in testing, so send times are not guaranteed, and there is no inbound fax.
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.
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