Abstract: A method and system for adaptively adjusting modem operating characteristics is disclosed. A modem includes a line interface circuit and a controller. The modem is programmed (such as by user-input) with an indication of a location (e.g., country or region) where the modem is operating. When going off hook, the controller sets the modem off hook impedance to a level that would be likely to be sufficient and acceptable under applicable governmental regulations. Upon going off hook, the controller then senses the actual line voltage at the modem, and, if it turns out that the modem is not within an acceptable operating range, the controller adjusts the off hook impedance of the modem so as to bring the modem into an acceptable operating range. The invention advantageously helps reduce the need to produce numerous different versions of a given modem, instead facilitating the production of a “global” modem.