samsung galaxy ACE GT S5830i

Solution
Try rebooting the phone. Is this the only time the other person can't hear the call well? Need to check their end as well. If rebooting does not help, have the phone looked at by a service center for the cell complany you got the phone from.
Try rebooting the phone. Is this the only time the other person can't hear the call well? Need to check their end as well. If rebooting does not help, have the phone looked at by a service center for the cell complany you got the phone from.
 
Solution