PhoneBridge

Has anyone out there successfully integrated any other on-premise PBX systems with ZOHO CRM? We use an IWATSU system that our phone engineers have successfully integrated with other CRM's, but the ZOHO support staff has so far been unable to provide much support for this. Our engineers simply need some answers about the languages used between the systems, and they're confident they could integrate the systems. Thanks in advance for any assistance or advice!