The P-Early-Media header is used in signaling the "authorization" of early media. Network nodes will often grant and enforce the authorization. The following are some general examples. A SIP UE to UE call will typically not exchange media until after answer, therefore early media is not authorized - P-Early-Media:inactive. A SIP UE call that interworks to the PSTN will have backward media authorized to allow call progress tones from the PSTN to be passed to the UE - P-Early-Media:sendonly. Calls that require user interaction (e.g., prompt and collection) prior to the call being delivered to the end user (and prior to the SIP dialog being confirmed) will authorize both-way media - P-Early-Media:sendrecv.
Jim -----Original Message----- From: sip-implementors-boun...@lists.cs.columbia.edu [mailto:sip-implementors-boun...@lists.cs.columbia.edu] On Behalf Of isshed Sent: Tuesday, October 07, 2014 2:30 PM To: Brett Tate Cc: sip-implementors Subject: Re: [Sip-implementors] Use case for P-Early-Media header (RFC 5009) Thank you Brett for the reply. I am still not able to connect to any example. It would be great if you can provide an example. Thanks!! On Tue, Oct 7, 2014 at 4:24 PM, Brett Tate <br...@broadsoft.com> wrote: >> SIP defines the "P-Early-Media" header to control the >> forward/backward early media. Could any of you guys help me understand the >> use case? >> I am not able to get the use case. >> >> Why servers have policy to block/control the early media communication? > > Hi, > > See sections 1 and 4. The unstated use case is billing. Some devices > want to communicate using early media to avoid billing situation by > not answering the call or reducing the time within an answered call; > some carriers want to prevent/control such behavior. > > -brett _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
