Yealink SIP-T20P on a IPv6-only network

At PCextreme we are looking into replacing all our current Cisco, Linksys and Polycom IP phones with new phones. The old phones are worn out and have to be replaced.

We have two demands:

  • IPv6 support
  • TLS support

After some searching I found out that neither Cisco or Polycom support IPv6 in their phones with SIP, so they we off the list.

More searching led us to Yealink and we ended up ordering a SIP-T20P.

A couple of days later I created a IPv6-only VLAN on our XS4All VDSL2 connection to I was sure there was NO IPv4 available for the phone.

It took some time to figure it out, but using the T20 over IPv6 is fairly easy.

  • Start the phone
  • Go to the Advanced Network Settings (password: admin)
  • Set the network type to IPv6

The T20 (Firmware 7.72.0.75) does NOT support DHCPv6 (The T4xx models do), it relies on Router Advertisements. We had to manually enter the auto provisiong URL (over HTTP) and afterwards the phone provisioned itself.

If we choose to go for Yealink it will probably be the T4x models since they support DHCPv6 and we want the auto provisioning to be fully automatic.

Published by

Wido den Hollander

I am the CTO at PCextreme B.V. and i will keep this blog just to post some interesting information about my daily work on Linux (and other) systems.