service tax should be charged in this case?

Yes, under the head Information technology services.

thanks Rajesh for your prompt reply, however there are some IT companies who have advised that some IT services are exempted from like this one.

Would you have any clue to this or reference where I can go through.

Thanks again,

There is no specific exemption for IT services. Off course general exemption like no service tax on export of services, refund of service tax paid on inputs used in export, SEZ units etc. is available to IT service provider too.