A thief has been trying to steal coins from phone boxes in Brighton and half a dozen other towns across Sussex.
More than 30 thefts or attempted thefts have been reported during March, according to Sussex Police.
Officers are urging the public to report anyone seen tampering with a payphone after incidents in Brighton, Lewes, Worthing, Haywards Heath, Eastbourne, Bexhill and Hastings.
PC Andy Lawrence said: “Phone boxes provide a valuable service to the community. The damage caused during the thefts is costly to repair and could cause inconvenience to members of the public.
“Sussex Police is working closely with BT and an investigation is under way to find those responsible.
“I am urging anyone who sees anything suspicious or anyone who appears to be damaging public telephones or stealing from them to please contact Sussex Police on 101.”
He said that people call also call the independent charity Crimestoppers anonymously on 0800 555111.