Currently you can use the USB ports for OBiWIFI, OBiBT and a USB dongle to upload images and ringtones etc.
"USB dongle" is referring to a USB thumb drive or USB storage. I don't believe the Obiline adapter is supported. USB hubs do not appear to be supported at this time.
Dongle dongle dongle dongle lol I have dongles on the brain ha...
USB drive pen is what I should of said, I forget that this is a US based forum at times.

The OBiLINE is not supported at the present time as mentioned above, it stated as being supported in the future:
OBiLINE FXO Adapter (Future): To connect to a Plain Old Telephone System (POTS), for example, to connect the OBi to the PSTN via phone jack provided by your telephone company or to connect to an analog PABX
Found on page 8 of the OBi1000 user guide.