I had an issue last June that drove me crazy for months. My service on my OBI200 had been working fine and then one day, people started complaining that I was cutting out while on the phone with them. I rebooted my router, my Obi, my switches, etc.. Then I looked at my AT&T router and noticed that the firmware on the router was newer than I remembered it being so I called AT&T to complain. It was a complete waste of time. They sent me a new modem, but of course, in their wisdom they sent me the same model I had already. Then I remembered I had a much older modem squirreled away and hooked that up and presto, the issue disappeared. I called AT&T, but they couldn't care less and said it was an issue with my equipment. So, I went on eBay and purchased a newer modem, BGW210-700 and since that day, no more issues. I'm guessing that the newer firmware on the modem giving me issues enabled SIP ALG which is known to cause problems. There was no option to disable it and AT&T support is worthless and just doesn't care to acknowledge the issue.