UsrInq

private void SendUsrInqRq()
{
    var inq = new UsrInqRq_MType()
    {
        IMSSubj = this.CurrentUserIMSSubj
    };

    var callback = this.messageBus.Send(inq).RegisterResponseHandler(this.OnUsrInqRs);
    var errors = Helper.CallbackErrors(callback, "SendUsrInqRq");
    if (!string.IsNullOrWhiteSpace(errors))
    {
        this.UpdateListbox(errors);
    }
    else
    {
        var str = "Sent UsrInqRq message " + callback.Receipt.MessageId + ", Time:  " + DateTime.Now;
        this.UpdateListbox(str, false, true);
    }
}

private void OnUsrInqRs(IMessageContext context)
{
    var responsePayload = context.DeserializeMessage();

    if (responsePayload.UsrInqRec != null)
    {
        if (responsePayload.UsrInqRec.IMSSubj != null)
        {
            this.signedInUserName = responsePayload.UsrInqRec.IMSSubj.Value.Remove(
                responsePayload.UsrInqRec.IMSSubj.Value.IndexOf("@", StringComparison.Ordinal));
        }
    }
}