Original text:
Secure RTP (SRTP) is a profile for RTP that provides confidentiality, message authentication, and replay protection for RTP data packets <del> and RTP control protocol (RTCP) packets RFC3711.  SRTP can use different handshake protocols, such as DTLS in DTLS-SRTP RFC5764 or ZRTP RFC6189. </del>  <del> 3.2.2. </del>  <del> ZRTP RFC6189 is an alternative key agreement protocol for SRTP.  It uses standard SRTP to protect RTP data packets and RTCP packets, but provides alternative key agreement and identity management protocols. Key agreement is performed using a Diffie-Hellman key exchange that runs on the media path.  This generates a shared secret that is then used to generate the master key and salt for SRTP. </del>  3.3. DTLS <del> SRTP </del> ZRTP  Transport-Layer Security Protocols: QUIC Application Payload Security Protocols:  SRTP Packet Security Protocols: separate module that will provide authentication, using EAP for example. <del> SRTP </del> IKEv2 tcpcrypt DTLS <del> SRTP </del>  QUIC

Reviewer comments:
This revises the description of SRTP and the relation between SRTP, DTLS, and ZRTP.
If we keep that headline, we need one for DTLS-SRTP too. Yes, that was intentional. SRTP is just the record protocol. The key management is usually done by DTLS or occasionally by ZRTP.
Comment from Ekr's review of -10: Pre-Connection Interfaces […] Also, I'm not sure you want to omit tcpcrypt here, in that it does have a way to do external authentication by exporting a session ID. Also ZRTP allows for some sort of fingerprint-based auth. tcpcrypt (and I believe ZRTP) both have session caches.
ZRTP uses , compared by the users, as an external authentication mechanism (similar process to the Safety Numbers in Signal, I believe). ZRTP does maintain a session cache.
In other words, ZRTP supports interfaces to Authentication Delegation and Session Cache Management, and DTLS-SRTP does not?
Thanks for the reply. I'm okay with merging these changes as they are, or you can add that one reference for ZRTP to have both.

Revised text:
Secure RTP (SRTP) is a profile for RTP that provides confidentiality, message authentication, and replay protection for RTP data packets  <ins> and RTP control protocol (RTCP) packets RFC3711.  SRTP provides a record layer only, and requires a separate handshake protocol to provide key agreement and identity management. </ins>  <ins> The commonly used handshake protocol for SRTP is DTLS, in the form of DTLS-SRTP RFC5764.  This is an extension to DTLS that negotiates the use of SRTP as the record layer, and describes how to export keys for use with SRTP. </ins>  <ins> ZRTP RFC6189 is an alternative key agreement and identity management protocols for SRTP.  ZRTP Key agreement is performed using a Diffie- Hellman key exchange that runs on the media path.  This generates a shared secret that is then used to generate the master key and salt for SRTP. </ins> 3.3. DTLS  ZRTP <ins> SRTP </ins> Transport-Layer Security Protocols: QUIC Application Payload Security Protocols: <ins> DTLS when used as a handshake protocol for SRTP ZRTP </ins> SRTP Packet Security Protocols: separate module that will provide authentication, using EAP for example.  IKEv2 tcpcrypt DTLS  <ins> ZRTP </ins> QUIC