I figured out how to configure a dual-stack IPv4/IPv6 "Access Point" for T-Mobile connectivity on my Samsung Galaxy Nexus, with stock Android 4.2.2. For some reason, when I visit http://myglobalip.com, I'm still getting an IPv4 address returned in addition to the IPv6 address.

Question: How do I configure the "Access Point" so that it only gets an IPv6 address, and not an IPv4 address?

My current IPv6 "Access Point" configuration looks like:

APN: epc.tmobile.com
Proxy: Not set
Port: Not set
Username: Not set
Password: Not set
Server: Not set
MMSC: Not set
MMS proxy: Not set
MMS port: Not set
MCC: 310
MNC: 260
Authentication type: Not set
APN type: Not set
APN protocol: IPv6
APN roaming protocol: IPv4
Bearer: Unspecified
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    I've also tried configuring the APN roaming protocol to IPv6 which hasn't helped at all. I'm still getting an IPv4 address as well. – Trevor Sullivan Apr 30 '13 at 2:14

Update [2013-04-30]: I believe the reason I am still able to access IPv4 websites, is because of DNS64+NAT64. The public IP address I'm getting from http://myglobalip.com is the public IPv4 interface of the NAT64 gateway.

I think the answer to this question is: T-Mobile uses some sort of transitional technology called 464XLAT to provide IPv4 connectivity over an IPv6-only GSM wireless network. There is more information about 464XLAT at this URL: https://sites.google.com/site/tmoipv6/464xlat.

Ultimately, it doesn't seem possible to disable IPv4 functionality altogether. Obviously, doing so would break a lot of applications from functioning properly, but I really wanted to do so entirely for testing purposes, to see what would and would not work.

The part that confuses me is that the 464XLAT RFC requires a "CLAT" daemon, which I don't believe exists on my stock Galaxy Nexus 4.2.2 Jelly Bean ROM. With this in mind, I'm not entirely sure what sort of configuration I'm running.

Here is the 464XLAT RFC.

If I use an app called Network Info II to view network interface information for rmnet0 on my Galaxy Nexus, I can see that I have ONLY an IPv6 address configured. In fact, the app even has an IPv6 "tab" specifically designed for viewing IPv6 information. I cannot see any IPv4 information when I have selected IPv6 as the APN.

More T-Mobile IPv6 information can be found:

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