This is my first setup with 3G on a Routerboard.  It took a little longer than I wanted to figure everything out, but I eventually got it working.

 

The steps that made it work.

  1. Place the UMTS drivers in the /firmware directory on the Routerboard (You should be able to get them from whom you purchased the card.)
  2. Install the Gobi 2000 and power on the router.
  3. Shutdown the router and install the SIM card
  4. Add the ppp-client with the settings below.
/interface ppp-client
add data-channel=1 dial-on-demand=no disabled=no info-channel=1 name=AT&T \
 port=usb2

Alternative Settings

/interface ppp-client
add data-channel=1 dial-on-demand=no disabled=no info-channel=1 modem-init=\
    "AT+CGDCONT=1,\"IP\",\"Broadband\"" name=AT&T port=usb2

For some reason the SIM card had to be installed after the drivers were installed.  When I set this up, I installed the SIM card and Gobi 2000 at the same time and kept getting ERROR in the “Current Operator” and “Access Technology”.  I then removed the SIM card and booted the router.  I tried inserting the SIM while the router was booted and still nothing.  After this I shutdown the router and reinstalled the SIM card.  Once the router powered back up everything was working with these settings.  The Alternative settings also work.  I had read somewhere that you needed the “modem-init” setting to make this actually work.  In my case it did not matter.

 

NOTE:  It can take the PPP Interface a minute to connect, be patient!  Also, if you can’t find the drivers, contact me and I’ll see what I can do.