It is possible to file an international application known as PCT application in India in the Patent Offices located at Kolkata, Chennai, Mumbai and Delhi. All these offices act as Receiving Office (RO) for International application.
Patent is a statutory right for an invention granted for a limited period of time to the patentee by the Government, in exchange of full disclosure of his invention for excluding others, from making, using, selling, importing the patented product or process for producing that product for those purposes without his consent.
Patent protection is territorial right and therefore it is effective only within the territory of India. However, filing an application in India enables the applicant to file a corresponding application for same invention in convention countries, within or before expiry of twelve months from the filing date in India.
Therefore, separate patents should be obtained in each country where the applicant requires protection of his invention in those countries. There is no patent valid worldwide.