{{tag>Troubleshooting Broadband_Routers SIP_ALG TP-LINK}}
====== How to Disable SIP ALG on the TP-LINK TD-W8960n, TP-LINK TD-W8968 and TP-LINK TD-W9970 Modem Router ======
SIP ALG (Application Layer Gateway) is a feature which is enabled by default in most TP-LINK routers and inspects VoIP traffic as it passes through and modifies the messages on-the-fly.

In few situations this is useful, but in most situations SIP ALG can cause problems using the service. Very often, SIP ALG is poorly implemented causing VoIP messages to be modified in a harmful way or simply corrupts them. In such cases you may experience issues registering your handset, one-way or no audio, unable to receive calls, and issues with [[features:blf|Busy Lamp Field (BLF)]] and Message Waiting Indicators (MWI).

For our Hosted VoIP service, including out Single User services, SIP ALG must be disabled on your TP-LINK router.

This guide explains how to disable //SIP ALG// on the following models:
  * **TP-LINK TD-W8960n** 
  * **TP-LINK TD-W8968** (hardware version 4)
  * **TP-LINK TD-W9970** (hardware version 2)
===== Step-by-Step Guide =====
  - Fire up a browser (Firefox, Chrome etc) and go to **192.168.1.1** (this is the default IP address)\\ //The default username is **admin** and the default password is **admin**//
  - On the left, click on **Advanced Setup** and then click on **NAT** and then click on **ALG**
  - //Uncheck// the box by **SIP Enabled** 
  - Click **Save/Apply**

====== Other TP-LINK Routers ======
Different TP-LINK routers may have different instructions. Please see list below for instructions for your particular device.

{{topic>TP-LINK&nodate}}
====== Further Reading ======
Further information can be found at [[http://www.tp-link.com/resources/document/TD-W8968_V2_User_Guide_1910010833.pdf|TP-Link TD-W8968 User Guide]].