All of this is way over my head. I don't have a cellphone. But Skype together with my laptop sort of act as one, if I am near accessible wifi (such as a coffeeshop). I use only VL6.0 on an old IBM T42. It apparently has an internal wireless card as I don't do anything other than click on my wicd icon to get connected.
Modems, I thought, were gadgets which allowed access to the internet via a regular telephone line, an access means which, I also thought, was quite slow compared to wifi.
I am likely spreading confusion and misinformation, so I will stop. However, in my case, I didn't have to buy anything to get on the internet with wicd. That's pretty cheap.