[SR-Users] auth challenge freeswitch with Zopier

Hello, I am using dsiprouter as a public facing server for pass through registrations to a fusion pbx box. This setup works great and has for a long time now. The issue I am having is that we are switching soft phone clients to copier. Zopier uses a push server. When an incoming call comes into the freeswitch server, it fires off an invite to the Zopier registered client. For some reason ONLY in this scenario Kamailio is doing an auth challenge to Freeswitch preventing to call to be sent to the soft phone. How can I stop this from happening? Other soft phones and hard phones work great with inbound calls except for Zopier. thanks,