In Canada, the best way to identify unknown callers or find out whose number is calling is to use reverse phone lookup services like Canada 411. Canada 411 enables users to perform a reverse phone lookup where you enter the unknown phone number into their system, and it scans its database to provide available information such as the caller's name, address, and phone type (cell or landline) if listed. This service supports identifying residential, business, and potential spam or telemarketer calls. Additional useful tools include YellowPages.ca's reverse phone lookup, which provides caller origin, company provider, and call type information. Caller ID apps for Canada can also help identify and block spam calls. In cases of calls pretending to be from official bodies like the Canada Revenue Agency (CRA), verifying the phone number through official channels is recommended to avoid scams. For private or no caller ID numbers, some apps or carrier services can help, although tracing such calls might require law enforcement assistance in serious cases. Thus, to know who is calling from a certain number in Canada, using online reverse phone lookup directories such as Canada 411 or app-based caller ID services is the recommended step.