400电话是运营商推出的一种主被叫话费分摊电信增值业务，目前已广泛用于各个行业售前售后服务咨询业务。与一般人所想的不同，400电话并非“电话”，仅仅只是一个长达10位的中转号码而已，除了通讯设备（手机、座机等）外，并不需要企业额外安装任何的硬件设备，因此也不需要任何安装费用。在开通了400号码后，企业只需要通过后台绑定手机、座机就可以接听外部的来电，由此可以低成本地帮助企业搭建一个在线呼叫中心。

The 400 telephone is a kind of telecom value-added service which is launched by the operator. It has been widely used in various industries before and after sales and after-sales service consulting business. And most people think different, 400 "phone", the phone is not just a 10 bit transfer number only, in addition to communications equipment (mobile phone, landline, etc.) do not need to install any additional hardware equipment companies, and therefore does not require any installation costs. After opening the 400 number, businesses only need to receive phone calls and landphones to receive external calls, which helps them build an online call center.