Session Description Protocol (SDP) Parameters

This table describes Session Description Protocol configuration parameters.

Table 1. Session Description Protocol (SDP) Parameters

Template

Parameter

Permitted Values

Change Causes

Restart or Reboot

sip-interop.cfg

voIpProt.SDP.answer.useLocalPreferences

0 (default) - The phone's use of its own preference list is disabled.

1 -The phone uses its own preference list instead of the preference list in the offer when deciding which video codec to use.

Note: If the H.323 call from a Polycom VVX 1500 selects a lower-quality codec (H.261) but the called device also support H.264, this parameter should be enabled to resolve the situation.

No

sip-interop.cfg

voIpProt.SDP.early.answerOrOffer

0 (default) - SDP offer or answer is not generated.

1 - SDP offer or answer is generated in a provisional reliable response and PRACK request and response.

Note: An SDP offer or answer is not generated if reg.x.musicOnHold.uri is set.

No

sip-interop.cfg

voIpProt.SDP.offer.iLBC.13_33kbps.includeMode

1(default) - The phone should include the mode=30 FMTP parameter in SDP offers:

If voice.codecPref.iLBC.13_33kbps is set and voice.codecPref.iLBC.15_2kbps is Null.

If voice.codecPref.iLBC.13_33kbps and voice.codecPref.iLBC.15_2kbps are both set, the iLBC 13.33 kbps codec is set to a higher preference.

0 - the phone should not include the mode=30 FTMP parameter in SDP offers even if iLBC 13.33 kbps codec is being advertised.

No

sip-interop.cfg

voIpProt.SDP.useLegacyPayloadTypeNegotiation

0 (default) - RFC 3264 is followed for transmit and receive RTP payload type values.

1 - The phone transmits and receives RTP using the payload type identified by the first codec listed in the SDP of the codec negotiation answer.

No

sip-interop.cfg

voIpProt.SDP.offer.rtcpVideoCodecControl

This parameter determines whether or not RTCP-FB-based controls are offered in Session Description Protocol (SDP) when the phone negotiates video I-frame request methods. Even when RTCP-FB-based controls are not offered in SDP, the phone may still send and receive RTCP-FB I-frame requests during calls depending on other parameter settings. For more information about video I-frame request behavior, refer to video.forceRtcpVideoCodecControl. For an account of all parameter dependencies refer to the I-Frames

section.

0 (default) - The phone does not include the SDP attribute "a=rtcp-fb".

1 - The phone includes SDP attribute "a=rtcp-fb" into offers during outbound SIP calls.

No