Acer F900 User Manual page 35

Here is how to adjust the proper volume:
1. If earphones are used with the Pocket PC to make calls, set the volume
according to actual personal needs.
2. If earphones are not used with the Pocket PC and not held close to the ear
for calls but similar to hands-free operation, it is recommended to set the
sound volume for the top two levels.
3. For holding the Pocket PC close to the ear directly for calls, it is
recommended that you set the volume to the lower four levels. It is
recommended not to use the top two levels because the volume is high and
may affect your hearing.
Turn on or turn off the speakerphone:
1. Enable the speakerphone: While answering a call, tap Speaker on to turn
on.
2. Disable the speakerphone: Tap Speaker off to turn off.
Using the Phone 3-5