Hi,
I am facing the similar problem on my RD 3510 handset.
From this discussion i see its solution as
Solution : Long Press the button you use to activate speaker (generally the OK button) and the speaker will turn off for general use.
Reason: It happens whn you long press the speaker on button in standby mode, after this whenever you make or receive a call it is routed to speaker and not to ear piece
But i did not get the details of it.
1. What is the button to activate the speaker ?
2. When should I press this button (during the call is on / call is not on)
Please reply as I am really frustrated with this feature ?
Thanks
Sohan