Phone rings in a strange tone

[WXD]

I'm using obi with google voice and Talk86 BYOD enhanced for my home phone (not cell phone, not forwarded). Lately I found out there was always an "incoming call" that rings the phone. But the ring tone is different from the regular ring tone for the phone. It's very short ring tones. And of course, there is no people on the other end calling. When picking up, nothing happens but it will ring again in a few mins.

Can you please check to see if there is any setting changed at your end? Thanks!