Courtesy call is a sugarcoated term used by telemarketers which really means sales call. This is one of the most deceitful and misleading phrases ever since there is nothing courteous about it.

Courtesy call（字面意思：礼节性电话）是被电话促销员巧妙伪装了的一个词，其实就指“促销电话”。这个词算是史上最具欺骗性和误导性的词了，因为“促销电话”本身没有一点礼节可言。

For example:

Hello. This is a courtesy call from Talk America which is inviting you to switch to our service.

你好。这里是来自Talk America的销售电话，我们想邀请您改用我们的服务。