How do I troubleshoot call flow within my network?

We are having a lot of trouble over the last month with our call flow. User's phones don't ring, soft phones don't ring. Ring Central has all but ignored our repeated requests for support and assistance. For a slightly more detailed description of my issue see here: https://community.ringcentral.com/ringcentral/topics/why_dont_the_desk_phones_ring_when_someone_calls_many_calls_go_straight_to_voice_mail What can I do to troubleshoot this issue on my local network(s)?