Contact U.S. Merchant Systems! If you wish to contact us, please use the form below. Phone Number Phone: (940) 323 - 8888 Sales Office Hours Monday - Friday: 9 A.M. to 6 P.M. CST Merchant Customer Service Office Hours: 24 Hours a day, 7 days a week Toll-Free: (877) 432 - 8871   © 1999 - 2006   U.S. Merchant Systems is a registered ISO/MSP for HSBC Bank USA, N.A. Buffalo, NY. Member FDIC.   |   Merchant Accounts   |   Credit Card Processing