If the SDP is not present and this field is set to ALLOW, Session Manager routes the call to the conference server as indicated in the Conference Factory URI mapping.
If the SDP is not present and this field is set to DENY, Session Manager does not route the call to the conference server as indicated in the Conference Factory URI mapping. Instead, Session Manager skips this conference server and goes to the next Conference Factory URI mapping until Session Manager finds an SDP status set to ALLOW.
If the SDP is present, Session Manager ignores the If SDP Missing field.