A wireless local loop (WLL) system capable of interfacing with an analog communication device is provided. The WLL system comprises: a SLIC (SLT interface Circuit) capable of matching analog data line characteristics of an analog communication device; and a MODEM for at least (1) receiving an analog data signal provided by the analog communication device through the SLIC, and converting the analog data signal into a class `0` digital data, or (2) receiving a class `0` digital data provided by an MSM, converting the class `0` digital data into an analog data signal, and providing the analog data signal to the analog communication device through the SLIC.