Solving Call Drop Issue in Elastix / Asterisk

If you change your Network and you find that the working Elastix / Asterisk box is now dropping calls every 15 to 25 secs.  One of the most probable reason is “NAT” .

The solution which worked for me is changing the sip_custom.conf found in /etc/asterisk/ directory.

Open it with your favorite editor such as vim or nano and add the following lines.

externip=1.1.1.1/255.0.0.0  < Your External Ip with Subnet Here >
localnet=192.168.1.0/255.255.255.0 < Your Internal Ip with Subnet Here >
canreinvite=no
NAT=Yes
Qualify=yes
promiscredir=yes

Hope this will help someone.

Thanks,
Salman