Direct Dial across multiple Freepbx servers

I have two Ubuntu 14.04 freepbx servers with IAX2 peer trunks. I can call extension to extension between the 2 pbx servers. When a customer calls our main phone number it goes to the Main IVR, which is on PBX1. The Main IVR has the option to direct dial an extension. When a customer enter the extension that is on PBX2, the IVR response stated that this an invalid response.

Is there a way to direct dial across 2 freepbx servers?