I use a TP-Link TD-W8920G and I have no dial tone? What's the solution?

Overview
Step 1: Login to TP-Link TD-W8920G
Step 2: Disable SIP ALG

Step 1: Login to TP-Link TD-W8920G
  1. Login to your  TP-Link TD-W8920G using 192.168.1.1
  2. Enter the username: admin, and admin
Step 2: Login to your engin 121
  1. Go to Advanced Setup > NAT > ALG
  2. Disable the SIP ALG option
  3. Your engin service should now be registered with a dial tone.