Call recordings need the same backup discipline as any important growing data, plus two considerations specific to recordings, retention rules and volume, so the approach:

The foundational principle, more than one copy in more than one place: recordings sitting only on the recording device are one failure from gone, so the baseline is getting them off that device to at least one other location automatically, ideally following the common three copies, two media types, one offsite pattern. The recording device, plus a local backup store, plus an offsite or cloud copy, is the durable arrangement rather than the single vulnerable copy you have now.

The automation, since manual copying fails: recordings pile up continuously, so the backup must be automatic, a scheduled job or sync copying new recordings from the device to the backup locations regularly, since anything manual gets skipped and the gap is exactly when the device fails. Configure the recording system to write to or sync with a backup location, or a scheduled script moving new files, so the backup keeps pace with the recording without human memory involved.

The recording specific considerations: retention and compliance, since call recordings often carry legal retention requirements, how long to keep them and sometimes privacy rules on access and deletion, so the backup approach should encode the required retention period and secure the recordings appropriately, encryption for sensitive calls and access controls, rather than just copying files. And volume, since audio accumulates, so the storage sizing and a retention policy that archives or deletes recordings past their required life keep the backup from growing without bound, the policy being as important as the copying.

The practical shape: automatic copying of new recordings from the device to a local backup and a cloud or offsite copy, encryption and access control for sensitive content and a retention policy matching your legal requirements that both keeps recordings long enough and clears them when permitted, sized for the ongoing volume. This turns the current single vulnerable copy into a durable, compliant, automatic arrangement, with the retention and privacy rules being the part generic backup advice misses for recordings specifically, worth confirming against whatever regulations apply to your calls.