A myth has apparently been circulating over the last year which suggests that dialling 999 from a mobile and immediately disconnecting will charge the battery.
Derbyshire Police has today appealed to phone users not to believe this rumour.
Every time police receive a silent or aborted 999 call they have to spend time ringing that person back to ensure they are safe, time which could be spent dealing with a real emergency.
Here are some tips from website Wikihow on how you could make your phone battery last longer.
Stop searching for signal.
Clean the battery contacts.
Do not follow the method of full phone charge and discharge.
Switch the vibrate function off and just use the ring tone.
Turn off the phone's back light.
Avoid using unnecessary features like the camera, especially the flash.
Turn off bluetooth, wifi, GPS etc.
Turn down display brightness.
Avoid using video or animated pictures as a background, use a black one if possible.
Keep the battery cool, even put it in the fridge.