sometimes a mere phone call from the police station to the person, who is sending ugly messages, works. One of my friends used to receive such calls, she had gone to the police station with the message and the number from which these messages were sent. She had to to write a complain there( FIR?). The police sent her back promising that she will not get such messages and they will look into the matter. The messages really stopped coming after a few hours! After two days she got phone call from the police station to ensure that she is not getting such messages. My friend has now respect for that particular police station and its efficiency.
This story is from the southern part of India.