In the UK the phone ring cycle is 3 seconds 0.4 second on, 0.2 second off, 0.4 second on, 2 seconds off. So 6 rings would be 18 seconds (i.e. before the 7th ring). But if you have to answer before the 6th ring, then it would be 5 x 3 seconds = 15 seconds.
Converting Seconds to Rings
| Rings | UK (Seconds) |
|---|---|
| 1 | 3 |
| 2 | 6 |
| 3 | 9 |
| 4 | 12 |
| 5 | 15 |
| 6 | 18 |
| 7 | 21 |
| 8 | 24 |
| 9 | 27 |
| 10 | 30 |