This document updates the Enhanced Variable Rate Codec (EVRC) RTP payload formats defined in RFC 3558 with several enhancements and extensions. In particular@ it defines support for the header-free and interleaved/bundled packet formats for the EVRC-B codec@ a new compact bundled format for the EVRC and EVRC-B codecs@ as well as discontinuous transmission (DTX) support for EVRC and EVRC-B-encoded speech transported via RTP. Voice over IP (VoIP) applications operating over low bandwidth dial-up and wireless networks require such enhancements for efficient use of the bandwidth.