Cannot pass message content while initiating sip call

[sabinaisayeva]

As per RFC we are allowed to send different headers and body with SIP invite. In this case we can pass content type as multipart/mixed and body consisting of multiple contents separated by boundary. In sip sorcery package it is possible to set content however it is overridden by sdp while placing the call. Example in https://datatracker.ietf.org/doc/html/rfc8787 And description in SIP RFC: https://www.rfc-editor.org/rfc/rfc3261