Can't answer calls to extension

I have lines 1 and 2 setup to my polycom phone. Both lines point to seperate pbxs. Line 1 works fine and i can answer calls no problem. Line 2 when my extension rings and i try to answer it, it just keeps ringing. Never answers. I believe it may have something to do with my network/firewall at work as i tried taking the phone home and both lines answered perfectly when at home. Not sure exactly what is causing the issue. Thanks in advance for the help!