# Configuring RFC 2833 settings

RFC 2833 capabilities are implemented through both MSPP voice channels and RTP IPv4 and IPv6 endpoints. The FilterAttribs parameter that the application specifies when it creates an MSPP voice channel indicates how the channel reacts when it receives RFC 2833 compliant packets through a DS0 endpoint. In addition, RTP IPv4 and IPv6 endpoint default settings support RFC 2833 capabilities. The following table provides details about the default RFC 2833 compliance settings for voice channels and RTP IPv4 and IPv6 endpoints:

MSPP object | Description
Voice channel | Encoder - transfers DTMF tones as RFC 2833 compliant packets but not as voice data, and does not generate unsolicited MSPEVN_DPF_DTMF_REPORT events at the beginning and end of each tone. Decoder - generates appropriate DTMF tones when it receives RFC 2833 compliant packets.
RTP IPv4 and IPv6 endpoints | Receives RFC 2833 compliant packets and generates MSPEVN_RFC2833_REPORT events at the beginning and end of the packet stream associated with each RFC 2833 event.

To specify how RFC 2833 capabilities are supported on an MSPP channel, the application sends MSPP filter commands to the voice channel. Applications can send the following commands to MSPP channels on which RFC 2833 capabilities are enabled:

Command | Filter | Description
MSP_CMD_ENCODE_DTMF_MODE | Voice encoder | Specifies a DtmfMode parameter for the encoder filter, allowing the application to re-configure how inband DTMF carriage works.
MSP_CMD_DECODE_DTMF_MODE | Voice decoder | Specifies a DtmfMode parameter for the decoder filter, allowing the application to re-configure how inband DTMF carriage works.

For more information about sending commands to MSPP endpoint and MSPP channel filters, refer to the Dialogic® NaturalAccess™ Media Stream Protocol Processing API Developer's Manual.

By default, RTP IPv4 and IPv6 endpoints support RFC 2833 capabilities. That is, when an application creates an MSPP channel that supports inband DTMF carriage, the connected RTP endpoint automatically generates appropriate events when it receives RFC 2833 compliant packets.