Sip protocol port 5060 not listened

We are trying to configure the VOIP service via OLT.
In the server side  apart from DNS packets none of the  SIP packets arrived in the server.

We have disabled the firewall.
and include the following package
opkg update
opkg install kmod-nf-nathelper-extra
/etc/init.d/firewall restart

But still 
netstat -ntlup not showing the port 5060  listen state.
SIP packets not arrived in the server.

Really apriciate  your help.

related to the SDK you've been working with, in your recent posts ?

Yes.same sdk.

That sdk is not supported here. Please refer to the people who have provided that sdk for help.