Have a look in the "OBiDeviceAdminGuide > End User Features Available on the OBi" for call transfer etc.
I should really subject you to a four day interrogation regarding exactly what digits you want sent where, but I'll just have a guess instead
Service Providers -> ITSP Profile A -> General -> DigitMap:
(<**2>1305xxxxxxx|<**21>305xxxxxxx|1xxxxxxxxxx|<1>[2-9]xxxxxxxxx|<1aaa>[2-9]xxxxxx|011xx.)
Replace aaa with area code for GV#1
Service Providers -> ITSP Profile B -> General -> DigitMap:
(1xxxxxxxxxx|<1>[2-9]xxxxxxxxx|<1305>[2-9]xxxxxx|011xx.)
To make the changes click on your OBi number on the OBi Dashboard, then find your way to Expert Configuration Pages. Uncheck both boxes to the right of the Value box, leave them unchecked, change the DigitMap, click on "submit" at bottom of each page before moving to another page, wait two minutes after each page for the OBi to reboot.
You are welcome to a full explanation of the above DigitMaps (just ask), but not today. In my time zone it's Friday evening and it's "beer time"