The article stated: “For years, fans of “Quan Ho” - centuries-old Vietnamese love duets - have been struggling to keep the music alive. In the face of pop music, karaoke and traditional ballads about young love and homesick soldiers, it had almost seemed like a lost art. But that fact, coupled with a sense that the national culture needed to be preserved in modern times has given a fresh impetus to the campaign to revive this centuries old art.

Last year, “Quan Ho” was recognised by UNESCO as a cultural heritage of humanity. With dozens of new troupes starting up and with village elders promoting the singing to a new generation, “Quan Ho” can still be rescued from the dusty vaults of world music's forgotten curiosities.

In fact, these days anyone can call for a song - literally. Rural singers in Bac Ninh Province in northern Vietnam, the ancestral home of “Quan Ho”, are handing out their phone numbers to music lovers and people who are just curious.

Dial them up and they'll serenade you over the phone - even if you don't speak Vietnamese. "If a foreigner calls for a song, they can simply say “Quan Ho”, and I will sing, we will all sing," says Nguyen Thi Quynh, Director of Dang Xa village’s club (84-1683-520-628).

Other groups to try are Hoa Dinh village’s club (84-95-372-3234) and the Dao Xa village’s club (84-97-633-5601).

“It's best to call in the early evening, when the singers have returned from the fields but haven't turned in yet for the night. And while the music will take you back to another era, don't drag the performers into yours: check your time zones before you dial,” the article recommended.