VoIP Voice and Fax Signal Processing

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WIDEBAND VOICE MODULES OPERATION

To exceed public switched telephone network (PSTN) voice quality, wideband VoIP on internet protocol (IP) network is one of the main options. Traditional PSTN and VoIP services limit the analog speech bandwidth. Wideband voice systems cater to analog signals from 50 to 7000 Hz sampled at 16 kHz. Narrowband voice is from 300 to 3400 Hz, sampled at 8 kHz. Wideband transmission acoustics characteristics are given in references [TIA/EIA-470C (2003), TIA/EIA-920 (2002), Alexander (2006), ITU-T-P.311 (2005)]. The main differences of wideband voice with reference to narrowband are the telephone acoustics, wideband electrical interfaces, higher processing for the voice chain, and user experience. VoIP wideband voice is possible if an end-to-end call is through VoIP and not routed through PSTN.

Wideband voice creates more natural-sounding conversation with the sense of presence, creating a feeling of transparent face-to-face communication that eases speaker recognition. Wideband signals are also treated under classification of audio. The history of wideband voice goes back to several years. G.722 was officially released in 1988 for wideband audio/voice [ITU-T-G.722 (1988)] and operates at 64, 56, and 48 kbps. There are many new codecs for wideband VoIP voice compression such as G.729.1 [ITU-T-G.729.1 (2006)] that operates up to 32 kbps, the adaptive multirate wideband (AMR-WB) G722.2 [ITU-T-G.722.2 (2003)] that operates at variable bit rates in range between ...