voip yealink phone not working

i'm trying to work from home. my company gave me a voip phone (yealink SIP-T42S). They have tested it works. I tested it at a friends fios house, it works. you just plug it in and it works. I have $100 cox internet only plan.

but when I plug it in (ethernet cable) to my cox panoramic router, I get one of two results.

a) the internet will still work for my computer but the phone will say obtaining ip address and the phone won't work

b) if i reboot the phone eventually the phone will work but then the internet will not work for the computer-even if i plug into the other port on the panromic router. 

i have tried for hours with cox support chat and phone support and no luck. I even paid the extra $10 per month and will try again tomorrow.

any suggestions? 

thank you in advance.