I don't know if this is applicanle, but I found this refering to the Obiline:
I hope this added info helps make your purchasing decision.
Echo solution:
If you experience echo during POTS use, here is the solution:
1: Login to your "OBi Dashboard."
1.5: MAKE SURE THAT YOU HAVE THE LATEST FIRMWARE INSTALLED.
2: Choose your device and then scroll to the bottom of the screen & click on "OBi Expert Configuration" then "Enter OBi Expert".
3: Now choose "Physical Interfaces" then "Line".
4: Scroll to "Port Settings" and edit parameter "ACImpedance"
5: In my case, "270+(750||150nF) and 275+(780||150nF)" was my solution.
Depending on the region you are in the world, the "ACImpedance" will have to be adjusted accordingly to your telephone network.
Cisco compiled a global list of AC Impedance settings, caller ID info, etc in order to "fine tune" your system for your country of use:
Preform a internet search using the following term without the quotes: "44705-SPA400Configuration_060109.pdf"