很多商家在宣传自己的400电话时，都会在前面加一个“免费”。到底400电话是不是免费的呢？400电话为何称为免费电话呢？400电话是免收长途费用的，也就是说，不管客户在哪里，拨打企业的400电话都只需要支付当地的市话通话费用。而免长途资费的企业热线，对于外地客户而言，也就相当于免费电话。
When many businesses advertise their 400 phone calls, they add a "free" in front. Is 400 phones free? Why is a 400 phone called a free phone? 400 calls are toll-free, that is to say, no matter where the customer is, the 400 calls to the enterprise only need to pay for local calls. And long-distance toll-free enterprise hotline, for foreign customers, it is equivalent to free telephone.