The Linked Device will just setup a speed dial to call an OBi Number.
In addition to calling, you can also pass data.
Define 2 speed dials as:
pp(510123456*1)
pp(510123456*2)
Replace 510123456 with the OBi number of the receiving OBi202.
In the receiving OBi202 use Obi Expert to make this change:
Voice Services -> OBiTalk Service -> InboundCallRoute:
{>1:ph},{>2:ph2},{ph,ph2}
Edit:
Use the above speed dials to ring a single phone port. Use the Linked Device speed dial to ring both ports.