We have an ATA 186 which we want to connect to our MFD. When we connect the device to the MFD and ring the port the MFD will not answer the call. If we connect to a VG224 the MFD detects ring ok and answers the call. If we plug a POT into the ATA the phone rings ok so we know there is an issue between the ring voltage of the ATA 40v and what the HP MDF is expecting. The MFD is a Q7519A but I can't find any info on the ring voltage required. Any Suggestions?