code: public ServerTransaction getAssociatedServerTransaction(ClientTransaction ct) {
  		
  		if(ct == null) {
  			throw new NullPointerException("Passed Client Transaction is null!");
  		}
  		
  		final ClientTransactionWrapper ctw = (ClientTransactionWrapper) ct;
  		final String associatedServerTransactionId = ctw.getAssociatedServerTransactionId();
  		if (associatedServerTransactionId != null) {
  			SIPServerTransaction st = (SIPServerTransaction) ra.getProviderWrapper().getSipStackImpl().findTransaction(associatedServerTransactionId, true);
  			return (ServerTransaction) ra.getTransactionWrapper(st);
  		}
  		else {
  			return null;
  		}
  	}
docs: /*
  (non-Javadoc)
  @see net.java.slee.resource.sip.DialogActivity#getAssociatedServerTransactionId(javax.sip.ClientTransaction)