VOIPo Residential is a managed ATA. You are not allowed access to add a diferent provider on the second line.

You can use a soft phone or a different ATA and the BYOD info to customize your own ATA. The original ATA can continue to be used, or remain as a back-up.

BYOD Page

Keep in mind BYOD is not officially supported, but the user community at http://forums.voipo.com/forumdisplay.php?f=28 can likely help.