**Ringer** — a person who pretends to be someone else in order to deceive others.
Here are some examples of using the word «ringer» in English:
1. I thought I had won the lottery, but it turned out to be a fraud — they sent me a ringer to collect the money.
2. The company was worried about fraud, so they decided to check all incoming calls to avoid getting ringers.
3. She was a perfect ringer for the role, she looked just like the actress.
4. He was afraid to go to the dentist, but he found out that the doctor was a nice person and not a ringer at all.
5. The organizers of the contest were very careful and did not let anyone in without checking documents, so it was impossible to get there by a ringer.
6. She was sure that her friend was a ringer, but she decided to give her a chance and invited her to her birthday party.
7. He tried to get a job in a large company, but they suspected him of being a ringer and decided not to hire him.
8. The police were looking for a ringer who was trying to steal money from bank accounts.
9. The teacher was suspicious of him, he seemed like a ringer, but he was really a good student.
10. She decided to check her email carefully to make sure there was no ringer trying to get her personal information.