It is there a speaker that can be plug in a headphone socket?

[AC Question]

My cell phone fell and it is not ringing any more. I would like to use an external speaker for this purpose.

 

[Benedict Petutschnig]

Well almost any speaker with an aux cable can do that. I can't show you some since I don't know what you'd like to spend, but almost every speaker (especially cheap ones) use audio output over an aux cable.

 

[smvim]

The headphone jack in your phone follows an industry-wide standard, often referred to as a 'mini' jack or '3.55 mm' jack. So take a look at the plug end of the earbuds that came with your phone, if you look closely there's three metal bands separated by two plastic insulators:
As long as the speakers you use have the exact same kind of plug you'll be fine. The 3.5 mm jack very standardized in most mobile audio devices and it's also the same as the audio in and out ports on your computer and/or laptop. So if you have an old pair of speakers from an old computer stashed in a corner those will work out. Note you might get better results if you use a powered set of speakers (those that use an external power adapter) as opposed to un-powered ones.

Another option would be to just use earbuds or a headphone and leave it plugged in all the time, might be handier than to always have those speakers around when you're making/receiving phone calls.