My mom got a NorTel phone in 1982 that uses 5p5c for the handset cord. Yes, 5-pin modular, when everything else is 4 or 6. I thought I finally found a vendor but he sent me the (usual) 4p4c type (for freaking $20). It;s kinda nostalgic to get it working. Had it in storage for two decades since she died.