I've checked WAN configuration and my router have SIP profile enabled)
If this is anything like the "SIP ALG" function that many routers have, then disable it. It often causes more problems than it solves.
If your modem is separate from your router, then test by connecting the OBi110 directly to the modem, wait a few minutes for the OBi110 to register with the VOIP provider, then try making a call. This will show if the problem is the router or not.
Is it possible to view any call logs on your SIP provider's web site? This may show that the signalling (SIP) part of the call is working even though the speech (RTP) is not working.