Code,Description,Reference
200,"The 200 response code indicates the completion of a successful
        framework protocol transaction.",[RFC6230]
202,"The 202 response code indicates the completion of a successful
        framework protocol transaction with additional information to be
        provided at a later time through the REPORT mechanism defined in
        Section 6.3.2.",[RFC6230]
400,"The 400 response code indicates that the request was syntactically
        incorrect.",[RFC6230]
403,"The server understood the request, but is refusing to fulfil it.  The
        client SHOULD NOT repeat the request.",[RFC6230]
405,Method not allowed.  The primitive is not supported.,[RFC6230]
406,Message out of sequence.,[RFC6230]
420,"Intended target of the request is for a Control Package that is not
        valid for the current session.",[RFC6230]
421,"Recipient does not wish to re-negotiate Control Packages at this
        moment in time.",[RFC6230]
422,"Recipient does not support any Control Packages listed in the SYNC
        message.",[RFC6230]
423,Recipient has an existing transaction with the same transaction ID.,[RFC6230]
481,"The 481 response indicates that the transaction of the request does
        not exist.  In response to a SYNC request, it indicates that the
        corresponding SIP INVITE dialog usage does not exist.",[RFC6230]
500,"The 500 response indicates that the recipient does not understand the
        request.",[RFC6230]