I've not had the specific issue mentioned by the OP. RingTo did have a midday service outage yesterday, 4/11/15.
When I've noticed issues with RingTo (not often for me but YMMV) it's usually with inbound calling rather than outbound. I also manage an OBi for a parent. I use RingTo's call forwarding to a free Callcentric NY DID to handle inbound calls for a variety of reasons such as more robust call filtering, CNAM and MWI. Because RingTo's call forwarding is actually simultaneous ringing, a small adjustment to the InboundCallRoute of the SP RingTo is provisioned on is necessary to keep Callcecntric and RingTo from ringing the OBi at the same time. I've found RingTo's outbound calling to be solid. Indeed during yesterday's outage outbound calling continued to work normally.
For my personal use, I use RingTo's mobile apps, partially because I beta test for them. Mostly, I just prefer to use my moto x or iPhone as opposed to a traditional home phone.