The pair's collaboration knocks Boyzone's 'Gave It All Away' back down to second place in the chart, while Rihanna's 'Rude Boy' moves up one spot to third.
Ellie Goulding's 'Starry Eyed' rises up three positions to take fourth place, while John & Edward's 'Under Pressure (Ice Ice Baby)' secures the remaining spot in the top five.
Meanwhile, notable new entries include the Glee cast's cover of Kelly Clarkson's 'My Life Would Suck Without You' at 29 and Timbaland and Justin Timberlake's 'Carry Out' at 41 ahead of its official release later this year.
The top ten singles in full (click for our reviews):
1. (2) Lady GaGa ft. Beyoncé: 'Telephone'
2. (1) Boyzone: 'Gave It All Away'
3. (4) Rihanna: 'Rude Boy'
4. (7) Ellie Goulding: 'Starry Eyed'
5. (3) Jedward ft. Vanilla Ice: 'Under Pressure (Ice Ice Baby)'
6. (5) Cheryl Cole: 'Parachute'
7. (6) Timbaland ft. Katy Perry: 'If We Ever Meet Again'
8. (11) Tinie Tempah: 'Pass Out'
9. (10) Justin Bieber ft. Ludacris: 'Baby'
10. (22) Mumford & Sons: 'The Cave'