2.5mm Headset Jack
A small round connector for accepting the pin-shaped plug from certain phone headsets. This connector can be also be used with certain other types of accessories.
While 2.5mm was the original standard for phone headsets, the slightly larger 3.5mm size is standard for music headphones and is now the more common size on phones.
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 device.
See: TTY
Either size can support stereo sound and/or a microphone, depending on the number of separate connector rings on the plug and jack.
2.5mm refers to the approximate diameter of the connector. 2.5 and 3.5 mm connectors look very similar, differing only in size.
Last updated Dec 7, 2013 by Rich Brome
Editor in Chief Rich became fascinated with cell phones in 1999, creating mobile web sites for phones with tiny black-and-white displays and obsessing over new phone models. Realizing a need for better info about phones, he started Phone Scoop in 2001, and has been helming the site ever since. Rich has spent two decades researching and covering every detail of the phone industry, traveling the world to tour factories, interview CEOs, and get every last spec and photo Phone Scoop readers have come to expect. As an industry veteran, Rich is a respected voice on phone technology of the past, present, and future.
