You can use an SIP device (ATA, IP phone or a softphone on either a smartphone or computer) for a 2nd line on the OBi200.
You can dial a number with an **2 prefix to route a call out SP2 (line 2).
Dial like this: **28005551212
You can modify the configuration to route a unique number without a prefix, like international numbers or a specific area code.
You just have to upgrade the OBi202's firmware to make it GV compatible.