code: public static Bridge create(final Call call1, final Call call2)
      	    throws Exception {
          assert (call1 != null);
      	final String callId1 = call1.getId();
      	final String callId2 = call2.getId();
      	return Bridge.create(callId1, callId2);
      }
docs: Convenience factory method to create a Bridge object from two Call objects
  @param call1 the call id
  @param call2 the call id
  @return the Bridge
  @throws IOException unexpected error.