The Beatles legend revealed he spoke with the 'No Time To Die' hitmaker via the video conference app after his fashion designer daughter Stella Mccartney, 48, who had designed the 18-year-old pop superstar's garments for her Glastonbury performance last year, set it up.
And the 'Let It Be' hitmaker admitted he loved getting to chat with the 'bad guy' singer and her sibling and collaborator, Finneas.
He said: ''Stella FaceTimed me with Billie and her family because she wore some of Stella's clothes on Glastonbury when she played it, so they were there. It was great to sort of chat with them and stuff.''
Billie and Finneas create their music in their bedroom but the 77-year-old music icon insisted that, whilst that works for them, The Beatles got a real thrill out of being at the studio and wouldn't have swapped their time at the legendary EMI and Abbey Road Studios for the world.
He told Howard Stern on SiriusXM: ''For them, it's brilliant. And what they produce from the bedroom is really very special.''
McCartney continued: ''The memories of going into EMI studios and to Abbey Road and the thrill of being some kid who'd been in his bedroom long enough, thank you very much, and getting out to this beautiful studio and being on almost kind of office hours -- two songs in the morning, lunch, two songs in the afternoon, good night.
''Four songs a day we were banging them out, it was so exciting ... I wouldn't swap that for anything.''
Meanwhile, the 'Come Together' hitmaker admitted he is ''sad'' that he won't get to headline Glastonbury's 50th anniversary this summer, after it was called off due to the coronavirus pandemic.
He said: ''What's disappointing for me is the people who bought tickets, who were looking forward to this and thinking here's something groovy to do in the summer, and suddenly the plug is pulled, and we can't come around and play for them.
''It's sad for us, too - we were looking forward to that.''
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