The video conferencing app is trialling the new security feature next month to help prevent cyber attacks.
One catch is that users must supply a phone number to benefit from encryption.
The feature works by hiding calls behind lines of unreadable code.
The company has made a U-turn as they previously insisted they wouldn't make it available for free, in part because Zoom wants to provide the police with access to the calls if necessary.
Zoom CEO Eric Yuan said previously: "Free users - for sure we don't want to give [them] that, because we also want to work together with the FBI, with local law enforcement, in case some people use Zoom for a bad purpose."