About Payload Types
You set the payload type when you are configuring a media profile to support Slow Start to Fast Start Translation.
When you configure media profiles, you might need set the payload type to identify the format in the SDP m lines. For RTP/AVP, the default transport method of a media profile configuration, this will be the RTP payload type number. Newer codecs have dynamic payload types, which means that they do not have an assigned payload type number.
When you use RTP/AVP as the transport method, you should only set the payload type when there is a standard payload type number for the encoding name; otherwise, leave the payload type blank.
The Oracle® Enterprise Session Border Controller uses the payload type value to determine the encoding type when SDP identifies the standard payload type in the m line, but does not include an a=rtpmap entry. These are two equivalent SDPs:
c=IN IP4 192.0.2.4
m=audio 0 RTP/AVP 0
c=IN IP4 192.0.2.4
m=audio 0 RTP/AVP 0 a=rtpmap:0 PCMU/8000
The first does not include the RTP map entry, but uses the standard payload type of 0. If the Oracle® Enterprise Session Border Controller receives an SDP like the first, it uses the payload type 0 to locate the corresponding media profiles configuration. When an a=rtpmap is present, the Oracle® Enterprise Session Border Controller uses the encoding name in the a=rtpmap line to find the media profile configuration and does not consider the payload type number.