Andersson, Ulvaeus and Anderson were invited to submit a song for the selection process for choosing the Swedish entry for the 1973 Eurovision Song Contest. After several days, Andersson and Ulvaeus came up with the tune for the Swedish version of "Ring Ring", with the working title "Klocklåt" (Clock Tune). Stig Anderson wrote the lyrics with the intention of making a "poppy" song, trying to remove the pomp and circumstance surrounding the Eurovision Song Contest at the time.

After this, the song was retitled "Ring Ring". To make it more accessible to a universal audience, Anderson asked American songwriter Neil Sedaka, together with his songwriting partner, Phil Cody, to pen the lyrics for an English version.

On 10 January 1973, the song was recorded at the Metronome Studio in Stockholm. However, when Björn & Benny, Agnetha & Anni-Frid performed "Ring Ring" in the Swedish heats on 10 February 1973, they only finished third. The song fared much better in the Swedish charts, both in its Swedish and English language incarnations, where it hit number one and number two respectively

More Info: en.wikipedia.org