Modem no longer works in Mac OS X 10.10 (Yosemite)

Applies to: Mac OS X 10.10 (Yosemite) and newer.

MultiTech's modems that use the TI USB-to-serial chipset require a kernel extension (KEXT, aka driver) for operation. As of Mac OS X 10.10 (Yosemite), Apple requires these drivers to be signed to be able to load the driver in the OS (OS X 10.9 and older didn't enforce signing of KEXTs). Some of MultiTech's drivers were not signed, so they will not load and thus the OS prevents the use of the modem.

To find out which driver you were using, do the following:
1) In the Finder's "Go" menu, select "Go to Folder...".
2) Enter "/System/Library/Extensions" and go to that folder.
3) In the "/System/Library/Extensions" folder, find "MultiModemUSB.kext" and select it (click once on it).
4) In the Finder's "File" menu, select "Get Info".
5) Find the version number for "MultiModemUSB.kext"

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If you were using the pseudo-CDC modem driver (version 2.x.x), then update to the latest signed version (2.2.5 as of this writing):

https://webfiles.multitech.com/mac-scripts/MTSModemInstaller-225.zip

Before installing 2.2.5, remove the old driver first by doing the following:
1) In the Finder's "Go" menu, select "Go to Folder...".
2) Enter "/System/Library/Extensions" and go to that folder.
3) In the "/System/Library/Extensions" folder, find "MultiModemUSB.kext" and select it (click once on it).
4) Move "MultiModemUSB.kext" to the trash (e.g. File-->Move to Trash). You will need to supply the admin username/password to move it to the trash.
5) Now you may install the new driver which will be found in "/Library/Extensions" (the new location Apple recommends for 3rd party drivers).
6) A restart of the system will be necessary (the installer should prompt to restart).
7) After removing the old driver and installing the new one, you may need to remove the fax device from the Printers and Scanners pane and then re-add it.


If you were using the original driver (version 1.x.x), then contact us by creating a support case at support.multitech.com.


NOTE: Apple's built-in fax capability works with fax modems in Mac OS X 10.11 (El Capitan) and older. Apple removed the built-in fax modem support as of macOS Sierra (10.12).


Models affected:
MT9234MU
MT9234ZBA-USB
MTCBA-C-U
MTCBA-E-U
MTCBA-G-U-Fx