Configuring LAN and VPN for AT&T Wi-Fi Calling

Router and modem configuration requirements to support AT&T Wi-Fi Calling.

Overview

To use AT&T Wi-Fi® Calling, your device must be able to communicate with the AT&T network. If your router's configuration has changed, or you're using a firewall, you may need to update your router settings to support AT&T Wi-Fi Calling.

For help updating router configurations, refer to your router manufacturer's website or contact your Internet Service Provider.

Requirements

1. Allow IPSec pass-through

Internet Protocol Security (IPSec) encrypts traffic sent through the internet and is used to provide a secure voice and data communication path.

Some routers block IPSec messages by default. AT&T Wi-Fi Calling requires IPSec pass-through to be allowed.

2. Open data ports 500, 4500, and 143

These ports are used to communicate with the AT&T network and must be set to open:

3. Set Maximum Transmission Unit (MTU) to 1500

MTU represents the maximum packet size that can be transmitted. Wi-Fi Calling performs best when the MTU is set to 1500.

4. Update equipment firmware

For best performance, always keep modems, routers, and switches updated to the latest software/firmware version. Updates are typically available on the equipment manufacturer's website.

5. Allow required Fully Qualified Domain Names (FQDNs)

A Fully Qualified Domain Name (FQDN) is the domain name for a computer or other host equipment on the internet. Wi-Fi Calling traffic must be able to traverse the following FQDNs: