Onboard DSPs provide variable voice encoding at bit rates for Adaptive Differential Pulse Code Modulation (ADPCM) and bit rates of 48 and 64 Kb/s µ-law or A-law for Pulse Code Modulation (PCM). Sampling rates and coding methods are selectable on a channel-by-channel basis. Applications may dynamically switch sampling rate and coding method to optimize data storage or voice quality as the need arises. SpringWare firmware also provides reliable DTMF detection, DTMF cut-through, and talk off/play off suppress..