The CIA recruits a lot of Iranians to spy for them. Since the Internet is a thing, they typically communicate with them that way. For example, in the 2010s the CIA ran hundreds of fake news, sports, travel, religious, etc. websites, where typing a password into a search box or other text field would open a hidden message area where operatives could read messages from the CIA and send back information. This network was eventually destroyed and hundreds of sources were arrested because the CIA made the error of using the same few messaging scripts and hosting the sites from a few contiguous IP blocks, but it's a good idea of how they generally operate. See here for more info: https://www.reuters.com/investigates/special-report/usa-spie... https://cirosantilli.com/cia-2010-covert-communication-websi...

However, since the US-Israeli bombing of Iran on Feb 28, the Iranian government has shut down the whole country's Internet access. This means that the CIA needs another way to send information out, hence the numbers station.