LAN configurations to support AT&T Wi-Fi Calling
For assistance in updating the configurations below, refer to the router manufacturer's website or contact your Internet Service Provider.
Internet Protocol Security (IPSec) must be allowed
Internet Protocol Security is a method of encrypting traffic sent through the Internet. It is used to provide a secure voice and data communication path. Some routers permit IPSec messages to be blocked. AT&T Wi-Fi Calling requires IPSec pass-through to be allowed.
Data ports must be open
Routers can be set to block traffic using certain ports. Ports 500, 4500, and 143 (as shown in the table below) are used to communicate to the AT&T network and must be open. Port blocking is sometimes implemented in the form of access lists.
|Data ports |
|Port||TCP or UDP||Service or protocol name||RFC||Service name|
|500||UDP ||Wi-Fi Calling ||5996 ||IKEv2 |
|4500||UDP ||Wi-Fi Calling ||5996 ||IKEv2 |
Maximum Transmission Unit (MTU)
The MTU represents the maximum packet size that can be transmitted. Wi-Fi Calling performs best if the parameter is set to 1500.
Network equipment software (firmware)
For best performance always use the latest software version on the following equipment:
Refer to the manufacturer’s website to download the latest software version.
Wi-Fi Calling Fully Qualified Domain Names (FQDN)
A fully qualified domain name (FQDN) is the domain name for a computer, or other host equipment on the Internet. Wi-Fi Calling should be able to traverse the following FQDNs: