See: Headphone Jack (3.5mm) 2.5mm connectors are still common for TTY devices for the hearing impaired. Therefore most modern phones require a 3.5mm-to-2.5mm adaptor in order to connect to a TTY ...

Also called a 3.5mm or 1/8" connector, it is a plug and socket widely used for analog audio signals in portable devices. For example, the headphone jack on iPods, tablets and portable DVD players ...

This however does put users who need a headphone jack to connect to legacy hardware at significant odds with market trends, limiting choices available to them to a much smaller pool of devices.

When your phone quits working or static develops on the line, your phone jack may need to be replaced. We'll show you how to ...