Securing Audio Using Master Key Identifier (MKI)

For secure audio communications, phones offer support for the crypto header with and without MKI in the offer SDP.

The following optional parameter allows you to include the crypto header in the SDP that uniquely identifies the SRTP stream within an SRTP session. The far end can choose to include a crypto with or without MKI.


1 (default) - The phone offers two cryptos in the SDP offer: one without an MKI, and one with a four-byte MKI parameter in the SDP message of the SIP INVITE / 200 OK.

0 - The phone offers only one non-MKI crypto in the SDL offer.