I found my internet phone to be much more reliable as well. I've had high speed cable internet since the late 90's and have many times reported either my land line or power off via the companies web sites. I went from ~$65/ month for just internet when I had warner + whatever for cable, $40 for land line and whatever for long distance. When warners customer service slid down to AOL levels I switched to wide open west and combined internet and cable for ~$80 plus $40 for land line phone and whatever for long distance. When I moved a couple months ago I dropped the land line for the $99 for all 4 services with faster internet and moving up from analog to digital cable.
The modem for my internet/phone even has its own battery in the side.