Here is my take
________________________________ From: Sunil Suraj-a22975 Sent: Friday, December 18, 2009 10:45 AM To: [email protected] Cc: Vavilapalli Srikanth-A19563; P Sudarshanakrishnan-A14377 Subject: Query on Early Media Authorization RFC5009 Hi All, I have some queries regarding Early media authorization: 1. It is mentioned in the rfc 5009 that "The P-Early-Media header field may or may not be present in messages containing SDP." So In the case of INVITE without SDP, can we add P-Early-Media header with "supported" value? Yes, UAC should always add support in the initial invite irrespective whether there is a SDP 2. If UAS receives INVITE without P-Early-Media header with "supported" value, then, can UAS add P-Early-Media header in 1xx responses? Yes, but without the header UAS cannot make assumptions on whether its early media will be played out and hence any business logic that depends on it cannot be taken for guaranteed. 3. In case of reliable provisional responses, if initial offer answer is completed, without Early media authorization i.e. without P-Early-Media header, then can UAS send PRACK/UPDATE with P-Early-media with value "supported" and whether there can be direction values in 200 Ok responses of PRACK/UPDATE? I think early media header was defined to primarily to control whether the UAC would play the early media from the UAS. The use cases you bring up of the caller wanting to send early media and reliably know whether the UAS would play it out I am not sure are addressed. Others? Regards, Suraj _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
