Storm is run on a voluntary basis by around 90 students at the university.

They should be used on a voluntary basis by investors.

We didn't have to work, it was on a voluntary basis.

If you leave industry to sort it out on a voluntary basis that's never going to happen.

All the positions in the union are on voluntary basis.

In most cases, such support is offered to families on a voluntary basis.

All other players have arrived and worked out on a voluntary basis.

It is open to school and college students on voluntary basis.

Such services must therefore be provided on a voluntary basis.

This work cannot of course be carried out on a voluntary basis.