VoIP.co.uk are dedicated to providing all services provided over IPv4 over IPv6. This includes our SIP platform, web interfaces, APIs, and tertiary services such as SMTP, DNS, etc.

Both a.ns.voip.co.uk and b.ns.voip.co.uk have IPv6 support, and have added v6 glue for them.

Our resolvers have full IPv6 connectivity, and can query zones with IPv6 only glue.

One of our secondaries, ns0.ncuk.net is not currently IPv6 enabled, however we are working with NCUK to add support.

Both http://ipv6.voip.co.uk/ and http://my.ipv6.voip.co.uk/ are IPv6 versions of their IPv4 counterparts. We have not yet seen statistics (although are working on collecting the data) that show adding both A and AAAA records to hosts does not restrict some users with broken dual stacks from accessing the sites.

As it is important both http://voip.co.uk/ and http://my.voip.co.uk/ are always available to users, we will not yet add in AAAA records; Once sufficient evidence has been collected of support, we will add the records

In the mean time, we may work on detecting IPv6 support and ask the user if they wish to go to the IPv6 version of the site.

We have added initial support to our network for IPv6 support. *test.voip.co.uk* has an AAAA record as well as an A record, and will handle INVITE dialogs.

However, the following issues currently exist with the SIP platform over IPv6, and we are working on resolving them:

• We can not currently process IPv6 REGISTER requests, and thus you can not register against the platform. However, INVITE requests can still be sent.
• The SBCs that handle outgoing requests to SIP URIs outside domains hosted on our platform are not yet IPv6 enabled, so will not send calls to IPv6 enabled public URIs yet.

Our inbound and outbound SMTP servers are not yet IPv6 enabled.

IPv6 is still in early stages of deployment on the internet in general. We are building out IPv6 support to ensure that it does not have an adverse effect on IPv4 only users, or users with broken IPv6 connectivity.

One particular issue worth mentioning is BT's broken IPv6 support on both their 21CN products and IPStream. This brokenness is down to a cisco bug in a certain set of BRASes, and does not affect all users - only those on a BRAS running broken IOS versions.

If you are having problems, you can verify if you are on a broken BRAS with these 2 commands:

ping6 -c 1 -s 10 ipv6.voip.co.uk
ping6 -c 1 ipv6.voip.co.uk

if you are affected by this bug, then the first ping will not work, and the second one will.