This is a tricky one. Reporting to parents is central to the teacher's role, and that usually includes the possibility of face-to-face meetings.
With so many parents working these days, it is usually convenient for most people if these meetings are held in the evenings. But you must also consider your own welfare in this situation.
Arranging to contact parents by phone and booking telephone appointments might be regarded as an administrative task, although it is not specifically mentioned in the list produced by the Department for Education and Skills. Under the workload agreement, schools are required to consider the teacher's work-life balance.
In your position, I think it is best to look for a compromise. Written feedback combined with follow-up calls for parents who want them is one possibility. These should be booked on the night of the parents' evening.
Then you would only need to speak to those parents who really wanted to talk about their child's or children's progress.