4 Year (1+3) On Site Repair Response Time Next Day Business for Lexmark T644 Printers. With Lexmark Onsite Service Next Business Day coverage, if your technical issue cannot be resolved over the phone, a Lexmark Technical Support representative will dispatch a qualified Lexmark service technician to your location for next-business-day service. The technician will service your defective printer onsite and will make sure your printer meets Lexmark's most stringent standards of quality and performance. This offering includes telephone and Web-based support, all parts and labour, and onsite service and testing.