The 'Bad Romance' singer joined jazz musician Brian Newman for a small performance in New York.
Lady Gaga And Her Mother Duet On 'Telephone'
The 'Born This Way' singer likes to perform the track when people call her on her phone.
Lady Gaga has revealed that she likes to perform her hit 'Telephone' with her mother when they speak on the phone.
The 'Born This Way' star said she occasionally bursts into a spontaneous rendition of the 2012 track when people phone her.
In a message on Twitter, she wrote: "Is it wrong that sometimes when people call me, I break out into 'Telephone,' my mom always does Beyonce's part."
Earlier this year, Lady Gaga and her mother, Cynthia Germanotta, co-founded the Born This Way Foundation, which is designed to inspire and empower young people.
Meanwhile, the 'Judas' singer is currently preparing to kick off her 'Born This Way Ball' tour in South Korea later this week.
It will mark the start of nearly two years on the road for the singer as she tours her 2011 album of the same name. The tour will see Lady Gaga play her biggest UK dates ever at London's Twickenham Stadium.
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The likes of Pharrell, Adam Levine and Billie Joe Armstrong will also appear on the record.
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