A DICOM Server of SonicDICOM PACS can connect to a third party DICOM Viewer.
However, this DICOM Viewer needs to be compliant with DICOM standard and needs to have Study Root Query/Retrieve or Patient Root Query/Retrieve.
Regarding technical details, please see DICOM Conformance Statement.
Regarding how to connect a DICOM Viewer to a DICOM Server of SonicDICOM PACS, please refer to To connect the DICOM viewer.
If it cannot connect well, please refer to FAQs below as well.