I have received a couple requests around IPv6 in the last month. So here's a list of carriers who offer IPv6 transit (IPv6 internet backbone, IPV6 internet bandwidth, IPV6 DIA).
The freshest article I can find is from PCWorld April 2008.
There's even an IPv4/IPv6 BGP Looking Glass here.
- NTT/Verio is all IPv6.
- Hurricane Electric (HE.net) is selling IPv6 on GigE ports for under $2K
- VZ/VZB used to be UUNET and MCI AS12702 <-- test bed
- Tata is an international carrier that is IPV6.
- Limelight is blending IPv6 into its CDN.
- Level3 AS3356 --L3 carries Lambda Net traffic and Internet2 so has to be IPv6 capable.
- Sprint - AS6175 is the testbed, which is "ready to provide native, dual-stack IPv6 services on SprintLink."
- Global Crossing AS3549
- XO is selling IPv6.
- Host.Net/WV Fiber
- Qwest - operates a native IPv6 network (OC-3) separate from IPv4 network. Qwest is the backbone for Abilene/I2, which is IPv6.
AT&T - not that I can find; although to sell to the federal government, especially the Dept. of Defense, you must offer IPv6.
There may be others - see CyberTelecom - let me know. (Leave a comment).
BTW, call the office - 813-963-5884 - for a bandwidth quote - IPv4 or IPv6.