ic Switched Telephone Network (STN). The limitations of narrowband audio can be removed when transitioning to all IP communications, as such a need arose for widerband codecs. Wideband codecs capture and encode sound from 20 kz to 20,000 hkz. With the advent of widerband codecs, there is a requirement to ensure that the microphones can accurately record these wider fidelity sounds and that the speakers used can accurately reproduce this wider fidelity audio. Equipment that is designed for wideband capture and reproduction has been used by professional audio recorders, but the use of this professional level equip- ment has only just started in IP Telephony. The most widely used wideband codecs are G.722 and AMR-WB. These wideband codecs require that the microphone and speaker have the ability to accurately records and play back 20 kz to 20,000 kHz sound frequencies. After the sounds are accurately recorded with the a high-quality microphone that is required for wideband codecs, a digital signal processing must be performed to encode the audio. Chapter 1: Overview of IP Telephony Digital Signal Processors Architecturally, the requirements of Digital Signaling Processing (DSP) can be done in one of two methods. The first is widely used in dedicated IP Telephony devices such as IP Phone or IP Video endpoints. This method uses a DSP chip that is optimized for receiving analog sig- nals and encoding them into digital signals in real time from the analog source to the digital stream and from the digital stream to the analog source. This capability requires that the DSP chip has buffers to accept the incoming packets, a set of processors that keep the math- ematical formulas to decode or encode the packets, and analog encoding circuitry to play back or sample the real-time media feed. The real-time media is either audio, video, or both. The second method of encoding these signals is called Host Media Processing (HMP). This solution uses the central CPU of a general processing device (normally a personal computer) to enco