U.S. consumers spent 4.5 million hours during the 2015 holiday season waiting for their content to be transferred from their old phone to a new one over an in-store Wi-Fi connection, according to a new report from Synchronoss Technologies Inc.

According to the report some 33.3 million devices in the eight-week holiday period from mid-November through mid-January, 19.6 million of which were sold in-store.

Based on data from a survey conducted by 451 Research, the report said just under a quarter of consumers request the transfer service and end up moving an average of 10.8GB of data. Using a 5GHz in-store router, the report calculated that the wait time for an average transfer is around an hour.

Taking 451 Research figures as a guide, Synchronoss projected that the problem is likely to get worse as content storage capabilities increase and put more pressure on in-store staff. Nearly 60 percent of all new U.S. smartphone sales and upgrades occur in-store, a trend which 451 Research indicates will be sustained through at least 2019.

Synchronoss, a cloud technology company that handles all iPhone activations for AT&T among other things, urged carriers to take action to mitigate the problem.

“Clearly, performing content transfer in-store for so many devices with such large data payloads is unsustainable,” said Synchronoss EVP of Product Management, Marketing and Business Development Daniel Rizer. “Carriers and retailers must deploy backup and transfer solutions so customer content is securely hosted in the cloud before they walk into stores and can be ported to a new device at any time.”