code: public void setOutboundInterface(InetSocketAddress inetSocketAddress) {
  		if(inetSocketAddress == null) {
  			throw new NullPointerException("outbound Interface param shouldn't be null");
  		}
  		String address = inetSocketAddress.getAddress().getHostAddress()
  			+ ":" + inetSocketAddress.getPort();
  		List<SipURI> list = this.sipFactoryImpl.getSipNetworkInterfaceManager().getOutboundInterfaces();
  		SipURI networkInterface = null;
  		for(SipURI networkInterfaceURI : list) {
  			if(networkInterfaceURI.toString().contains(address)) {
  				networkInterface = networkInterfaceURI;
  				break;
  			}
  		}
  		
  		if(networkInterface == null) throw new IllegalArgumentException("Network interface for " +
  				address + " not found");		
  		
  		outboundInterface = networkInterface;
  	}
docs: /*
  (non-Javadoc)
  @see javax.servlet.sip.Proxy#setOutboundInterface(java.net.InetSocketAddress)