c1765nfw Fax DRPD Ring pattern

I am trying to set up my new mfp. The instructions for setting the distinctive ring pattern say to contact my phone provider to find out what pattern number to assign. My provider has no idea what Dell is talking about. So, I tried simply setting the mfp to all 7 different pattern numbers and called the fax line with my cell phone. The mfp never once picked up, no matter what pattern number I set. How do I get the machine to pick up a fax? Especially when I have a distinctive ring on a dedicated fax line?

Thanks