There is no control on the user side (that I can find) that sets the number of rings, it's just however long it takes NOMOROBOs servers to kick in.
Have you contacted the good folks at NOMOROBO about this?
Quite some time ago, the NOMOROBO folks said that they did not have an answer for my number of rings issue. Perhaps I should reach out to them again.
My daughter had NOMOROBO on her Comcast land line, and her phone rang only one time when a call was interecpted.
I've wondered if the issue has to do with my Motorola phones.
Yes, mine only rings once as well.
Don't know why it would mattter what kind of phone you have, since both your phone and the phone/server at NOMOROBO should be ringing simultaneously, if Comcast's 'call forwarding' is working correctly.
Please do come back with the answer if you ever get one, I'd really like to know what's happening.
After thinking about it some more I'm wondering if your Nomorobo service is really set up right. The four rings thing sounds like the default value for the number of rings before Comcast's voice mail system picks up. Are you sure that it's really Nomorobo that's picking up after 4 rings, or could the calls just be going to voice mail?
Also, maybe double check your Call Forwarding setup page to make sure Nomorobo's number is on the list and enabled (box has a check mark in it).
You've probably already checked these things and ruled them out, but I thought I'd mention them just in case.
Thanks for the suggestions. I'll look into them.
As for voice mail, I had Comcast disable that service quite some time ago because some of the robocallers were leaving voice mail messages.