How does importing system works? from the supplier to me? -

Your Government Department of Trade should be able to give you the required information.

Ebay dispute problem? -

i sold a cdma modem in ebay,now the buyer says that reliance is not providing him internet with that modem and i said that is not my problem,so now he threatens me that he file a case on me through police,he is in kerala and i am in chennai.can he file a case in kerala on me.

It depends on the return policy that with your sale you did. If it was still within the refund time at the time of the complaint then he has to send it back and then you should refund. You should contact ebay about this question because they have several policies regarding this type of transaction.

No they cannot file a criminal case against you. The worst they can do is file a complaint with pay pal and the worse they can do after trying to mediate is to refund the buyers money. Good Luck.