UMODEM(4) BSD Kernel Interfaces Manual UMODEM(4)


umodem — USB Communication Device Class serial (CDC ACM) driver


To compile this driver into the kernel, place the following lines in your kernel configuration file:

device usb
device ucom
device umodem

Alternatively, to load the driver as a module at boot time, place the following line in loader.conf(5):



The umodem driver provides support for USB modems and serial devices that implement the Communication Device Class Abstract Control Model (CDC ACM). It also provides device-side CDC ACM support. Supported modems are basically standard serial line modems, but they are accessed via USB instead. They support a regular AT command set. The commands can either be multiplexed with the data stream or handled through separate pipes. In the latter case the AT commands have to be given on a device separate from the data device.

The device is accessed through the ucom(4) driver which makes it behave like a tty(4).


Devices supported by the umodem driver include:

3Com 5605

Curitel PC5740 Wireless Modem

Kyocera AH-K3001V Mobile Phone(WILLCOM)

Kyocera WX320K Mobile Phone(WILLCOM)

Metricom Ricochet GS USB wireless modem

Sierra MC5720 Wireless Modem

Yamaha Broadband Wireless Router RTW65b

ELSA MicroLink 56k USB modem

Sony Ericsson W810i phone

Sonim XP5300 Force


for callin ports


corresponding callin initial-state and lock-state devices


for callout ports


corresponding callout initial-state and lock-state devices


tty(4), ucom(4), usb(4)


The umodem driver appeared in NetBSD 1.5. This manual page was adopted from NetBSD by Tom Rhodes <trhodes [AT]> in April 2002.


Only modems with multiplexed commands and data are supported at the moment.

BSD April 26, 2017 BSD