It depends on the DHCP part and your provider lease time. When you access the Internet through a modem and landline, it's an highly dynamical system, where it's difficult to guarantee every caller/user gets its own IP. Especially when IP sharing is used among the clients. Even more difficult it is with the mobile Internet. It's a constant connection loosing/reconnecting. Actually resetting and freeing up IPs for new devices, the whole time. With cable Internet (the TV cable) one is having a kind of stationary access point. The network provider can see it's topology and it never changes once a leafe has joined the network. I typically have the same access creds over months. Even when I restart my cable modem, it's still the same IP. When I was on modem, I could get a new IP every second of I wanted. Now I have to think twice, because I just can't get a new IP, even if is forcedly, not.