There are already a number of products out there which claim that they will let you listen to someone's mobile conversations, forward their SMSs and tell you the numbers they have dialled ...

市面上已经有在售产品声称可以让你听到别人的手机对话，转发他人的短信，还能告诉你他们拨打了什么号码……

youdao

But the warrant requirement applies only to the actual conversation, not to the numbers dialled from a phone.

ECONOMIST: Government surveillance

It also does not cover telephone conversations passing through international lines or telephone metering, increasingly used by police to secure telephone records of the numbers dialled by suspects.

ECONOMIST: A snooper��s charter