While I am not familiar with your particular unit, it sounds like the hookup you found is for connecting an outside TV. The main cable/satellite TV input would typically be near where your electric, and water connections are.
I haven't seen a landline connection in an RV since my travel trailer from the 90s. Most people use cellular for phone, and if you are in a campground for a long time, you can sometimes get internet as an add on from the local cable company.
We spend 5 weeks at a time in a campground where I work out of the RV. We have an account with Comcast, and my own cable modem. I run my own wi-fi network, and have an IP phone for work, and an Ooma phone line that our home phone forwards too.
2013 V 3105
2016 F350 King Ranch CC 6.7 diesel dually