1. A source-controlled Variable bit-rate Multi-mode WideBand (VMR-WB) codec comprising a unit operable with an Adaptive Multi-Rate wideband (AMR-WB) codec, where in a VMR-WB encoding/AMR-WB decoding case, speech frames are encoded in an AMR-WB interoperable mode of a VMR-WB encoder using one of bit rates corresponding to Interoperable-Full Rate (I-FR) for active speech frames, Interoperable-Half Rate (I-HR) at least for dim-and-burst signaling, Quarter Rate-Comfort Noise Generator (CNG-QR) to encode at least relevant background noise frames and Eighth Rate-Comfort Noise Generator (CNG-ER) frames for background noise frames not encoded as CNG-QR frames, said unit responsive to a case that voice activity is not detected for using CNG-ER encoding, further responsive to a case that voice activity is detected, and responsive to a voiced versus unvoiced classification such that if a frame is classified as unvoiced, the frame is encoded with one of Unvoiced HR or Unvoiced QR encoding, further responsive to a frame not being classified as unvoiced for using a stable voiced classification, and if the frame is classified as stable voiced, encoded the frame using Voiced HR encoding, else assuming the frame to likely contain a non-stationary speech segment for using an appropriate FR encoding, whereas a frame with low energy, and not detected as at least a background or an unvoiced frame, is encoded using generic HR coding to reduce the average data rate; an unvoiced classification decision being based on at least some of a voicing measure {overscore (r)} x , a spectral tilt e t , an energy variation within a frame dE, and a relative frame energy E rel , where decision thresholds are set based at least in part on an operating mode comprising a required average data rate.