Um…It’s not just cox cable, you can negotiate with your phone company over DSL.
In purchasing DSL, I raised my concern that one reason why I wanted to go with cable modem was that cable modem is like $20/month on top of cable for me, while as if I were to get DSL, i would need to get a phoneline too, which while DSL would cost $17, just keeping a phone line on is roughly $12/month (just local service with limited local dialing)
I got my DSL for $17/month, and ATT gives me a $12 credit/month on my phone line. Supposedly it’s good for only a year, except at the end of the year, I always call and tell them to extend the offer or I’m going to cancel both my phone line and my dsl service. Never had an issue getting the terms extended. Though I mostly use my cell for phone, it’s nice having a landline that you’re not paying for.