Microsoft completed its takeover of Finnish mobile phone manufacturer Nokia’s smartphone and mobile phone divisions on Friday, but there’s one thing it hasn’t got its metaphoric hands on: Nokia’s iconic and annoying ringtone.

Two decades after it was heard – it celebrated its 20th anniversary on April 7 – the world’s best-known ringtone is still used as a default on all Nokia-branded phones. It could even be considered a marvel of the technological world for having survived this long, despite various remixes, renditions and mangling.

The latest variation of the tune came on its twentieth birthday, when Nokia attempted to keep its "business as usual" spirit up and organised an a capella group to capture the tune in all its nuanced and melodic glory.

While the tune is now ubiquitous, it has its origins in piece for classical guitar by Spanish composer Francisco Tárrega, who worked at the turn of the 19th century. His Gran Vals, composed in 1902, is a typical selection from his vast body of work, but Nokia executives picked up on it over a hundred years later and decided to immortalise a seemingly random phrase from it.

That phrase turned out to be an excellent choice. Part of the reason the tune still survives is because once it enters your head, it is unlikely to leave it easily. One exasperated listener even spent a fair amount of time devoted to determining whether the tune begins on an upbeat or a downbeat – and concluded that, like an optical illusion, the answer was both and neither, which is why it remains so tantalising.

Quite apart from its official monophonic, polyphonic and, at times, cacophonic avatars, people regularly take it upon themselves to play and compose variations. Canadian pianist Marc-André Hamelin integrated the tune into his Ringtone Waltz (appropriately called Valse Irritation d’àpres Nokia – Irritation waltz in the style of Nokia) of 2009.

The Nokia tune has even become shorthand for all mobile phones. At a popular classical music concert series in Mumbai, the lead cellist regularly plays it before a performance commences to remind people to turn off their phones. Lukáš Kmiť, the violist in the video below, might have done well to have played it before his concert. Even so, when a Nokia ringtone interrupted his performance, he delivered a look of death, but recovered with grace.

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