How to share RTP's ssrc value between calling and called party in sip call?

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While doing srtp call, we need to create a security policy from sender side(calling party) and receiver side(called party).We have to provide the same ssrc value while creating security policy for encoding and decoding the RTP packets.Could you please tell me how can we send the ssrc value from sender to receiver before RTP session start ?

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SSRC values are generated by RTP module by defined by RFC 3550. You need to call some RTP api's to get this value.

As per RFC 3550 this defination there " As per RTP module this SSRC value is very unique accross calls. The SSRC identifier is a randomly chosen value meant to be globally unique within a particular RTP session (see Section 8). A participant need not use the same SSRC identifier for all the RTP sessions in a multimedia session; the binding of the SSRC identifiers is provided through RTCP (see Section 6.5.1). If a participant generates multiple streams in one RTP session, for example from separate video cameras, each MUST be identified as a different SSRC."