There are many. The most frequently mentioned here are Anveo, Callcentric and
VoIP.ms. I have personal experience with Anveo and Callcentric but not
VoIP.ms. I find Callcentric's website easier to navigate but both are fine companies.
VoIP.ms has an excellent reputation as well. Please understand that none of these options will be free, though VoIP in general is extremely reasonably priced. FWIW, Callcentric currently has a promotion offering to port your number in for free.
If free is a requirement, pairing Google Voice with Bill Simon's recently revived Google Voice Gateway might be an option. Like RingTo, Google Voice does not natively support CNAM. There is a one-time fee of $5 for the gateway. Porting your number from RingTo to GV will cost about $30 and require first porting the number to a prepaid mobile carrier and then to GV. Google Voice does not port landlines and RingTo's numbers are considered landlines.
Some have had success forwarding RingTo numbers to Callcentric. Callcentric offers free DIDs (phone numbers) but they are New York state numbers. Callcentric would then provide the inbound CNAM. You would need an additional open SP slot, however, to keep RingTo and add Callcentric, so that might not work for you.
Have a look around the various providers websites. I'm sure you'll find a fit for your needs.
Cheers! Roland