Additional Information
RN-001037-03 REV19 – 07.2014
12
Configurable Codec Negotiation Behavior
Previously, when the phone received and SDP Offer with several codecs defined for
the media stream, the phone would reply with an SDP Answer containing all the
codecs present in the Offer (as per RFC 3264).
A new configuration parameter (“
sip single codec reply in sdp
”) has been introduced
in Release 3.3.1 SP4 allowing Administrators the ability to change the phone’s codec
negotiation behavior so that the phone will indicate only one preferred codec in the
SDP when replying to an SDP offer (as per 3GPP TS 24.229).
Defining the “
sip single codec reply in sdp
” as “
0
” (disabled) will maintain the default
behavior of the phone (as per RFC3264). Defining the “
sip single codec reply in sdp
”
as “
1
” (enabled) will change the phone’s behavior to indicate only one preferred
codec (as per 3GPP TS 24.229).
Configuring Codec Negotiation Behavior
Use the following parameter to configure the phone’s codec negotiation behavior.
SIP Features
Note:
The first codec on the compatible codecs list will be selected as the single preferred
codec when the “
sip single codec reply in sdp
” parameter is enabled.
Parameter
–
sip single codec reply in sdp
Configuration Files
aastra.cfg, <model>.cfg, <mac>.cfg
Description
Specifies whether the phone should reply to and SDP Offer (with sev-
eral codecs defined in the media stream) with an SDP Answer contain-
ing all the codecs present in the Offer (as per RFC 3264) or with an SDP
Answer containing just one preferred codec (as per 3GPP TS 24.229).
Format
Boolean
Default Value
0 (Disabled)
Range
0-1
0 (Disabled - RFC 3264)
1 (Enabled - 3GPP TS 24.229)
Example
sip single codec reply in sdp: 1
