Service tax on ambulance service provided in private co.

Pl. help me in understanding Service tax charged on the ambulnace service provided in a private company for following situations:

1) Private company providing the service to private company and if new private company is started and in starting getting business of providing ambulance service in private company then what would be the process and limit to pay service tax.

2) Trust providing the service to private company (also is it possible?)

Thanks in advance