Try this StarCode:
*01, Modem Call, set($Noji1,200),set($Noec1,1),set($Cdm1,3),call(16235941000)
16235941000 is the number you want the device to call.
Then program the device to just dial the StarCode "*01".
You can test this with an analog phone.
It dialed out for me by dialing "*01".
Edit:
If the device is dialing too fast for the OBi, you can have a single character StarCode like this:
*, Modem Call, set($Noji1,200),set($Noec1,1),set($Cdm1,3),call(16235941000)
Now just dial "*".