For incoming calls the phone rings but I cannot hear the caller. The volume is set to the maximum. For outgoing call I cannot hear the ring tone nor the person receiving the call.

The ringer circuit could be defective.

Is the ringer turned off? Or is the volume on the ring tone set too low? Another possibility is that the phone isn't set to receive incoming calls - the Siemens phones I've owned allowed one to specify which handsets could handle incoming calls and outgoing calls on each line.

Thanks for visiting FixYa!

In most cases, the ring tone callers hear (incoming ring tone) is controlled by your cellular service provider.

Try this first: (On the Internet) Sign-in to your cellular account. On your account page, look for a link that directs you to your incoming ring tones (or similar). There, you can change your incoming ring tone.

If you're unable to do that, contact your cellular provider's Customer Support. They can assist you in changing your incoming ring tone.

Some how your phone was reset or had the tone turned off. Just follow the below guide and your audio should come back on. I would do a soft reset (turn off the handset, remove the battery then reinsert) before performing the instructions.

Tone settings
To select a ringing tone for voice calls, select Tones >
Ringing tone.
To select a ringing tone for video calls, select Tones > Video
call tone.
To set the ringing type, select Tones > Ringing type. You
can also set the device to sound a ringing tone that is a
combination of the spoken name of the caller and the
selected ringing tone, when someone from your contacts list
calls you. Select Tones > Say caller's name.
To set the volume level of the ringing tone, select Tones >
Ringing volume.
To set the various alert tones, select Tones > Message alert
tone, E-mail alert tone, Calendar alarm tone, or Clock
alarm tone.
To set the device to vibrate when you receive a call, select
Tones > Vibrating alert.
To set the volume level of the device keypad tones, select
Tones > Keypad tones.

I have included a link to download your user manual if needed, it comes as a PDF file so you need to have adobe PDF down loader

http://nds1.nokia.com/phones/files/guides/Nokia_E63-1_UG_en.pdf

first of all u can increase volume during call by pressing right button (middle one). but i think ur phone is set to max and u dont hear much - in this case probably some "metal dust" sticks on your speakers membrane - open case clean speaker gently or replace with new one...

Check Windows Sound mixer for application volume. Down in system tray at right side of taskbar double click sound icon for XP or click sound icon once and click Mixer for Vista. Look through volume settings for your phone application. Make sure it is not muted and volume is up.

increase the volumes of ring tones ,unscrew the phone to check if the ringer is not faulty or damaged,repair or replace it ok

The only reference to flash timing I can find in the manual is shown below for you, also here is link to manual :
I hope it helps !
http://www.uniden.com/products/productdetail.cfm?product=TRU8885-2

If you have Call Waiting service and a call waiting
tone sounds while you are on a call, press talk/flash
on the handset or flash/find hs on the base to accept
the waiting call. There is a short pause, and then you
will hear the new caller. To return to the original
caller, press talk/flash on the handset or flash/find
hs on the base again.

Setting the Ring Time
Ring Time allows you to set the number of rings the caller hears before your
answering system plays the outgoing message. You can set the ring time to answer
after two, four, or six rings. If you enable the Toll Saver (TS), the answering system
picks up after two rings if you have new messages and after four rings if there are
none.
1) Enter the Answ. Setup menu, and then the Ring Time
submenu (see "Entering the Menu" on page 16).
2) Press volume up/down to select a Ring Time (Toll
Saver, 2 Times, 4 Times, or 6 Times).
3) Press the OK soft key. You will hear a confirmation tone.
Setting the Record Time
Record Time sets the duration for recording the incoming messages. You have three
record time options. The options "1 minute" or "4 minutes" set the duration for
recording the incoming messages. "Announce only" answers the call but prevents
the caller from leaving a message.
1) Enter the Answ. Setup menu, and then the Record
Time submenu (see "Entering the Menu" on page 16).
2) Press volume up/down to select Record Time
(1 Minute, 4 Minutes, or Announce Only).
3) Press the OK soft key. You will hear a confirmation tone.

Change your Cellphone!