What is the tilde (~) used for in phone numbers?

The tilde (~) also known as the “squiggly twiddle” is used in Russian phone numbers (and phone numbers based on the Russian system, such as Kazakhstan, Abkhazia, and South Ossetia) to denote ‘wait for the dial tone.’

International calls from Russia involve dialing the exit code of ‘8 – wait for the dial tone – 10’. It is sometimes written ‘8 ~ 10’. The tilde (~) means ‘wait for the dial tone.’