Accruals should be made because no invoices received yet, so how come

Accruals should be made because no invoices received at that time, so how come we use invoice received on 31.3.20X7 to accrue for the year end of 28.2.20X6? Example below is from BBP textbook.

1.2 Example 1: accruals
Horace Goodrunning, trading as Goodrunning Motor Spares, ends his financial year on 28 February each year. His telephone was installed on 1 April 20X6 and he receives his telephone account quarterly at the end of each quarter. On the basis of the following data, you are required to calculate the telephone expense to be charged to the statement of profit or loss for the year ended 28 February 20X7.
Goodrunning Motor Spares – telephone expense for the three months ended:
$
30.6.20X6 23.50
30.9.20X6 27.20
31.12.20X6 33.40
31.3.20X7 36.00

Solution

The telephone expenses for the year ended 28 February 20X7 are:
$
1 March – 31 March 20X6 (no telephone) 0.00
1 April – 30 June 20X6 23.50
1 July – 30 September 20X6 27.20
1 October – 31 December 20X6 33.40
1 January – 28 February 20X7 (two months) (2/3 × 36) 24.00

The charge for the period 1 January – 28 February 20X7 is two-thirds of the quarterly bill received on 31 March. As at 28 February 20X7, no telephone bill has been received because it is not due for another month. However, it is inappropriate to ignore the telephone expenses for January and February, and so an accrued charge of $24 is made, being two-thirds of the quarter’s bill of $36.

The accrued charge will also appear in the statement of financial position of the business as at 28 February 20X7, as a current liability