Features: 1. No need to install batteries, just plug in the phone line and it can be used 2. Small and exquisite appearance, only 6cm wide, easy to place, does not take up space 3. Up to 85 decibels of sound, 50 meters of effective distance is more suitable for noisy places, big space or more rooms. 4.The volume of ringtone can not be adjusted, It is aloud to assure the call can not be missed. If you want the ringtone is slight,please give up buying 5. Redial the last dialed number,Please refer to the instruction manual for details 6. Flash function,Please refer to the instruction manual for details 7. Pause function,Please refer to the instruction manual for details 8. Mute Function,Please refer to the instruction manual for details 9. Destk /wall mountable, please check the holes of sizes installation 10. Hold function,Please refer to the instruction manual for details