Try these couple of things:
The speakerphone feature lets you hear audio through the speaker and
talk without holding the phone.
To activate the speakerphone while in answering or calling modes,
press the Navigation Key to the right.
The phone returns to normal (Speakerphone Off) after ending a call
or when the phone is turned off and back on.
To adjust the ringer, key tone, voice call and speaker phone volume levels:
1. Press left soft key [MENU] (7) (1) (2).
2. Select the type of volume you wish to adjust.
3. Select the desired volume level.
4. To confirm, press OK.
Let me know if this works for you or if I can help you with anything else.