I've never had any issues with either my Nokia 520, 635, or 640. I've never heard this issue reported before. When you put the phone on speaker, can you hear the tones being generated and do they sound right?
As far as I know, there are no settings to adjust this. Since it is the software that generates the tones, it is also not a hardware fault.
The best thing to try is to do a soft reset, that is, turn the phone off and then on again. Then see if it works. If not, sign up for an account, return to this thread, and provide additional information that may help us to help you.
09-19-2015 07:42 AM