How to contact Mercury Payment Systems (MPS)? Philippe NICOLAS January 24, 2023 22:14 Updated Follow You can contact Vantiv / Mercury Payment Systems (MPS) directly at 800.846.4472. MPS representatives are available 24/7. Related articles Assign Static IP to iSMP4 Card Reader (Worldpay) Network printer (LAN and WiFi) – Printer Issues Powered by Zendesk