In the most simple terms - our system normally generates Call-ID's for all calls - HostGator bypasses portions of our system to inject calls directly into our network and they generate their own Call-ID's - because they have a high volume of calls. In this case the Call-ID that they generated happened to match one of your Call-ID's - the system then new that the call was not a valid call and so it used a failure route - so on your account used a failover route which happened to be your cell phone number. So essentially HostGator's call was actually TO someone else but they were misrouted to you - because their Call-ID matched a Call-ID that was already in our system and the two calls got mixed up as all Call-ID's must be unique. The only reason this happened is because HostGator bypasses part of our network to route them directly. Typically with all of our customers we generate the Call-ID's ourselves - since HostGator bypasses our regular system and goes directly into our core system - they generate their own and in this case it happened to overlap.

I've looked for cases of this in our logs and I've only see it a handful of times out of millions and millions of calls.

We are going to work with HostGator to make sure that all Call-ID's are unique so it does not happen again.