Samsung A886 - Manual (Page 174)

Solving Problems
168
The audio quality of the call is poor

Check the signal strength indicator on the display ( ); the number of
bars indicates the signal strength from strong ( ) to weak ( ).

Try moving the phone slightly or move closer to a window if you are in a
building.
No number is dialed when you recall a Contacts entry

Check that the number has been stored correctly, by using the Contact
List Search feature.

Store the number again, if necessary.
If the above guidelines do not help you to solve the problem, take note
of:

the model and serial numbers of your phone

your warranty details

a clear description of the problem
Then contact your local dealer or Samsung after-sales service.