My Speaker Phone only works on VOIP applications

Hello Experts,

Recently the speaker phone on my Iphone 4 does not work on GSM (mobile) calls, but work perfect on VOIP application like Fring, Skype etc.  During the GSM call when I turn on the speaker phone the person on the other end cannot hear me, but I can.

When I gave it for the repair the service center quoted $217 to fix the hardware. looks like the hardware is fine because the VOIP application works perfect.

I tried restoring my phone few times now. No Luck.

Has anyone come across this issue any solution any tip?

Thanks in advance

Regards

Mohan