I think I understand your question. The one-word answer is "yes".
Let's explore further. You aren't connected "directly to the internet", technically-speaking. Your office has some form of internet service entering the building, and it goes into some networking equipment, depending on the sophistication of your network. At minimum, that internet connection goes to a router and one or more Ethernet switches. Then, all the network-connected gizmos in the office connect to Ethernet switch ports (RJ-45 jacks), or to a WiFi access point on the same router/switch.
Your computer is currently connected to the Ethernet switch. You could leave it that way, and also plug the OBi's WAN or LAN port directly into the same Ethernet switch (using another port/jack of course), or you can plug the OBi's WAN port into the Ethernet switch, and then plug your PC into the LAN port on the OBi. The latter option will take advantage of the OBi's built-in router and Quality of Service (QoS) function, to prioritize the OBi's voice packets vs. the computer's packets. If you only have one Ethernet jack nearby, this solution will work.
However, the built-in router in the OBi 202 isn't designed for high throughput, and its Ethernet interfaces are limited to 100Mbps vs. 1Gbps. If you are doing network-intensive work on your computer, you may notice the difference.
I wouldn't recommend using WiFi to connect the OBi. Load on the WiFi access point from other users in the office may cause poor VoIP performance on the OBi.
So: which option do you want to select? There are some settings involved, depending on your choice.