H1B DS160关于绿卡和TELECODE 如何填写

请问大家，现在已经开始申请绿卡DS160上
Has anyone ever filed an immigrant petition on your behalf with the United States Citizenship and Immigration Services?

这个问题是要答YES，是吧？那之后的解释应该如何填写呢？

还有TELECODE是中文电码么？请问在哪儿查找啊？

谢谢！