 The process of analog-to-digital conversion is intrinsically lossy, and in addition, the digital signals used by the telcos utilized a nonlinear encoding (μ-law and a-law) which made it very difficult to find an encoding that could survive the digitizing process.Modem manufacturers discovered that, while the analog to digital conversion could not preserve higher speeds, "digital to analog" conversions could.Because it was possible to obtain a direct digital connection to a telco, a "digital modem" - one that connects directly to a digital telephone network interface, such as T1 or PRI - could send a signal that utilized every bit of bandwidth available in the system, and while that signal still had to be converted back to analog at the subscriber end, that conversion would not distort the signal in the same way that the opposite direction would have.