Business support

Using VoIP service over a non-CenturyLink ISP

To use VoIP service over a non-CenturyLink ISP, known as an alternate carrier or over the top, you'll need to follow these procedures: 

Installation requirements

  • Power over Ethernet switch or power outlets for each phone

  • Ethernet wiring (Cat5e or better) from your switch to the location of each phone

  • Ethernet data port available for each person receiving a VoIP phone (as well as one for every location—such as a conference room, break room, or kitchen)

  • Configuration of your customer provided equipment (router, ethernet switch, and firewall)

Troubleshooting VoIP service over a non-CenturyLink ISP

If your Hosted VoIP service is not working and you're using an alternate carrier, try these tips:
  • Some routers allow for plug-and-play setup of VoIP phones, but not all routers are built the same. Due to the number of routers available with other providers, CenturyLink doesn't test, certify, or provide configurations for these devices.

  • You should always back up your router configuration before making changes. CenturyLink repair cannot assist with this activity.

  • If your router supports SIP ALG, try turning that feature off.

  • Demilitarized zone (DMZ) is a feature on most routers where it will direct all traffic from the internet to a device on the network. Try pointing your DMZ to your Hosted VoIP phone.

  • Features like busy lamp field and shared call appearances might not function properly depending on your Internet provider’s router settings.
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