Downtime for me is when I pick up the phone and there is no dialtone OR I don't even try because I'm uploading or downloading a large file. I wouldn't totally replace my land line with this system if I often made a lot of calls. I personally might consider it, though, because I don't make many calls except for business and I do have a cell phone as a backup. Like I said, these minor inconveniences are worth it to me based on value. I pay less than 1/3rd of what I would probably pay for another land line.