"Calling" was written by Halliwell along with Peter-John Vettese, while production was helmed by Stephen Lipson. Halliwell called it her favorite song on the album. After she recorded a demo version of the song, she rushed over to singer and personal friend George Michael in London and played it to him. She commented that Michael would only offer praise if he really thought it was deserved. As he was "brutally honest" and it could be hard to take, she was so confident about this song that she was willing to risk it. When the song ended, he said, "You know what, Geri, that's very good". According to Halliwell, "from George Michael that means something. I really believed I had a winner."
Released on 26 November 2001, "Calling" debuted and peaked at number seven on the UK Singles Chart on 2 December 2001, lasting 10 weeks on the chart. Altogether, the song sold 70,515 copies and became the 192nd best selling single of 2001 in the United Kingdom. Elsewhere, "Calling" entered the majority of the charts it appeared on, peaking at six on the Hungarian Rádiós Top 40 and at number 11 in the Wallonian region of Belgium. In her autobiography Just for the Record, Halliwell revealed that the chart position upset her as "Calling" was her favourite song from the album, and she was certain that it was a sure-fire number one. Due to her disappointment with the chart position of the single, no further singles were released from Scream If You Wanna Go Faster and Halliwell moved to Los Angeles, California for several months and took a break from the music industry.
The music video for "Calling " was filmed in Barcelona in October 2001.
The black and white music video for "Calling" was directed by Pierluca DeCario and filmed in Barcelona, Spain in October 2001. It shows Halliwell, dressed with a black sweater and barefoot, singing the song while lying in a meadow and standing and walking in front of concrete walls. The video was released on 1 November 2001.