The 10-day visit is to start next week and will be Kate's first official overseas trip.
The Daily Mirror cited a St. James' Palace source it did not identify as saying the prince spent his birthday Tuesday at the Royal Air Force base in Anglesey, while Kate was at Kensington Palace in London.
The Duke and Duchess of Cambridge talked by phone briefly, however, the newspaper said.
"It was a normal working day -- a very low-key birthday," the palace source told the Mirror.
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