U-Verse High Speed Internet service uses this type of modem (this is the "U-Verse" service that is a traditional ADSL type service, not their IPTV VDSL stuff -- it used to not carry the U-Verse name). I'm stuck with it at my extended family's summer home since there's no other service available. It's been incredibly flaky. Since the default configuration won't allow me to set the modem to respond to ICMP and we physically unplug electronics other than the modem when we're not there, I've run out of ways to monitor it remotely from my home two hours away (thereby eliminating the possibility of getting a monthly credit for every month this thing has been flaky).
I've had service techs out for the last two years trying to make it more reliable, but the biggest problem has been "proving" that the service has been down, and very frequently. Now I can get my local nagios instance graphing the terribly reliability. That should get ammunition to request monthly statement credits, hopefully increasing their motivation to fix the wiring in the area (everyone in this small town that has U-Verse complains about the reliability of the connection).