Teracom TDSL300W2 VOIP Setting

[ket000]

I have recently replaced my bsnl router with the new one Teracom TDSL300W2 and it stopped my voip phone from working correctly (Provider : nettalk). In my previous router there is a check box for voip phone which is not present in the new router. I tried to disable firewall and try putting nettalk device in dmz which does not work correctly as it keep changing its ip address. Can somebody post manuals for this router or provide instructions so that I can setup the port forwarding or correctly setup the voip settings. SIP is already disabled.