Thank you for the reply...Yes, you are right...I need to go to Seoul, Korea for making phone to my parents...^^
I didn't know there is hidden menu on FIOS router, but I followed your direction for disabling IGMP Proxy and double check the SIP ALG disabling..(on top of that disable ADVANCED>ROUTING>IGMP)...not worked...
There are many people around here in DC area to have a problem to call to Korea using this service (I read many similar prolbem from other message board) and some of them already swich the ISP and no problem after...
It was using without any problem before ~6/22, also I still can make a call from other place...so problem must be verizon side...
Any other things that I can try?