If you live in France you get a my favorite ISP, (don t have any commercial relation but be one of his customer), free (appears at fbx.proxad.net on irc )who has what they call a freebox (http://en.wikipedia.org/wiki/Freebox), which is one of the inventor as what we know now as triple pay for internet, phone, and video, and they offer as a small but good geek bonus an option like a sip account, wifi, and redirections of your phone line linked to your adsl account to that sip account you own. now if you have a phone on which the sip works (bought a n85 a week ago), then you can do what as you want, have a single device. However note that peoples still have 2 numbers to contact you and you still have 2 outgoing choices for phone calls.
They got other bonuses like tivo like recoder with HD channels, about 180 channels, and phone to landline to 60 countries for 30â, good news server retention, usualy, 6MB adsl, ipv6, Gb sized mail with zimbra and web account with apache mysql. (note that they had to inovate and redo the dslam infrastructure to do that), hoo too much goodies.
I even like their geeky tv ads, and i mean by anyway , long time ago in france when isp were charging us for internet access on top of the phone comunication fee (which was way higher than now), and free was the first to have no charge on top of the phone fees, and that's where they got their name and then their infrastructure and budget to do what they do now.
Now also be prepaired to wait for 3 months to get your dsl line, because the historic operator always make a few errors when switching the connecting to their lines.