Keep Forever.

Diplomat Volodin is going to work in the States for a responsible job. But, having crossed the ocean, he immediately went over to the Americans. And not empty-handed: he calls the American embassy from a pay phone and gives the appearance of a Soviet intelligence officer. The traitor is sure that he will not be identified “by the phone's strangled voice. There can be no such technology. But, on the instructions of the Chekists, such a technique was developed in Marfino's "sharashka" near Moscow by convict engineers and scientists.