Business support

Configuring your router to work with your VoIP phone

A router is a networking device used to connect your computer or other equipment to an internet service provider (ISP). If you have home internet service, you have a router. How the router will work with your VoIP phone depends on the model (and on how old it is). Many consumer routers allow you to simply plug in a VoIP phone to use it; a few need to be configured to work with a VoIP phone.

Important: If you take your phone off the CenturyLink-provided network, CenturyLink service level agreements, quality of service (QoS), and the ability to connect to the hosted VoIP platform are not supported. Troubleshooting is limited to providing phone and router/firewall settings.

To configure your router to work with your VoIP phone:

First, see if your router allows plug-and-play setup of a VoIP phone. If not, follow these troubleshooting tips:

  • If you need to configure your router, back up the current router configuration before making changes.

  • If your router supports Session Initiation Protocol Application Layer Gateway (SIP ALG), turning that feature off can improve performance.

  • Network Address Translation (NAT) can cause problems with voice over IP. For consumer-grade routers, we recommend that NAT be turned off.

  • Most routers have a demilitarized zone (DMZ) feature that can direct internet traffic to a particular device on the network. Try pointing your DMZ to your VoIP phone.

  • Depending on your Internet provider’s router settings, features like Busy Lamp Field and Shared Call Appearances might not work properly.
Port & IP information

Public IPSBC addresses (IPv4):

  • Chicago—
  • Highlands Ranch—

Open these ports for SIP from all CenturyLink session border controllers (SBCs):

  • 5060
  • 5061

Open these RTP ports for all CenturyLink SBCs only:

  • 2222-2317
  • 3000-3000

The IP address of the CenturyLink SBC varies and can be provided by the CenturyLink provisioner working the order.

If a firewall feature is configured in the router, it must allow the following traffic to pass between all Hosted VoIP phones and the CenturyLink SBC (in both directions):

  • SIP—allow TCP ports 5060 and 5061  and UDP ports 5060 and 5061
  • MGCP—allow TCP ports 2427 and 2727 and UDP ports 2427 and 2727
  • RTP—allow UDP ports 16384-32767 (Some firewalls will dynamically open and close UDP ports for RTP as required and do not need the entire range of UDP ports for RTP opened all the time.)
  • NTP—allow TCP port 123 and UDP port 123
  • TFTP—allow TCP port 69 and UDP port 69
  • HTTP—allow TCP port 80 and UDP port 80; TPC port 2208 and UDP port 2208; TPC port 443 and UDP port 443
Note: CenturyLink doesn't test, certify, or provide configurations for routers available with other providers. CenturyLink repair cannot assist with router configuration or backup.
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