vncs Vp New Modem Fax Encoding Choice Table

1.3.6.1.4.1.562.2.4.1.44.3.384

This attribute specifies preferences regarding the encoding of modemFax and fax traffic. During the setup of an audio call, the local and remote ends negotiate one common encoding to use during modemFax traffic and one common encoding to use during fax traffic. The local end's ordered list of preferred encodings is given by all modemFaxEncodingChoice elements that are not set to none. Prior to negotiation, the local end removes encodings from its list that it cannot use for a particular call. For example, the card for a particular call may not be able to support certain encodings, or in the case of relay, the rate of the sending machine may not be supported. After this local check, the local end sends its modem/fax encoding preferences to the remote end. The remote end uses the two most preferred encodings that it can support from the list to determine the encoding used during modemFax traffic and the encoding used during fax traffic. If the remote end cannot support any encodings on the local end's list, a call does not proceed and an alarm is issued. The current encoding and encoding rate are available in Vsr Svs currentEncoding and Vsr Svs currentRate. The encoding choice g711Only specifies that pulse code modulation (PCM) defined by ITU-T G.711 should be performed to encode modem/fax traffic for calls using this profile. In this case, all modem/fax traffic is carried uncompressed at 64 kbit/s. The encoding choice g711G726 specifies that either pulse code modulation (PCM) defined by ITU-T G.711 or adaptive differential pulse code modulation (ADPCM) defined by ITU-T G.726 should be performed to encode modem/fax traffic for calls using this profile. The actual encoding performed depends on congestion in the network and the settings of the g711G726 row of the modemFaxRates attribute. The encoding choice of relay specifies that modulated modem/fax traffic is demodulated and sent through the network as Passport cells at the base rate of the sending machine. The types of modulation/demodulation supported are V.29 up to 9.6 kbit/s and V.27 up to 4.8 kbit/s. Only fax traffic can use relay. If modemFaxEncodingChoice is relay, none, none, modem traffic is not supported. If modemFaxEncodingChoice is none, none, none, all traffic is treated like voice traffic. Fax relay cannot be performed on 1pDS1V, 1pE1V or J2MV cards. The negotiated modemFax and fax encodings are available in Vsr Svs Framer negotiatedEncoding.