Does anyone face this weird problem with your iphone 3gs?

today i received a call but i cant hear the caller but caller can hear... i need turn on loud speaker then no problem

I did soft reset, take out sim card etc etc.. but still the same..

then i took out my headphone plug in then take out.. problem solved..

Mine is a maxis set, normally if i sent back to maxis to check, how long would it take?