There is not a lot of selection. Many of these devices are not actually VoIP depending on the modem type. A cable modem many times has a special voice over cable. It is VoIP but it is special and only connects to the cable ISP. Many ports on DSL modems are not actually VoIP they are analog ports that just connect though.
There are not many devices that have actual VoIP. It makes it even harder when you need some form of modem in the box.
I would use a external adapter, at the moment I forget the cheap one I used, but something like magicjack. You could then buy any modem/router your liked