I've been using RC for my business since 2014, never any major issues...now I have some of my clients telling me that when they called my business number, they get a message stating that the voice mailbox is full ? However, when I call from my personal number, it rings right through to voicemail without issue. Today I was with a client and they told me they've been having issues with contacting me, I asked them to call my business number and let me hear this for myself...sure enough after the phone connected it stated "the voice mailbox is full" and hung up on them. I then immediately called from my personal cell phone to the same business number and it went through with voice greeting and then voicemail ?? Point of reference we both have phone numbers with identical area codes (not that that should matter).
I'd reach out to support if it was me, but I'd also look at the Call Handling and Forwarding settings for your account to see if anything looks unusual, especially for handling of calls from your cell number. Is your cell number in your forwarding options?