Are there Rate Limits on ticket endpoints other than account ids?

I am running an api that makes calls to zendesk on behalf of my customers. They give us their account ids and that's what is used in the request. 

We seem to be hitting API limits but not getting the expected message. The accounts aren't using the api so heavily they should hit limits. But we as an organization might be. I was wondering if we could be limited ourselves by our IP range or something.