how do you increase receiver speaker volume?

[musefreek]

first time iphone user here.

i have to listen very carefully when making phonecalls. can't figure out how to increase the receiver speaker volume.

anyone know?

 

[southerndoc]

Use the volume up/down button while on a call.

 

[itsmemuffins]

Buttons on the side of the phone.

+ makes volume go up.

-makes volume go down.

Switch makes iPhone silent and vibrate.