IPv6 roaming in the United States
I spent some time in the United States last month. Equipped with SIM cards from both Tele2 Sweden (MCCMNC 24007) and Telenor Norway (MCCMNC 24201), I set out to test IPv6 while roaming, as I usually do while abroad.
The previous posts in this series are:
- IPv6 roaming in Belgium and Romania
- IPv6 roaming in the United Kingdom
- IPv6 roaming in Czechia
- IPv6 roaming in Sweden
There were two mobile networks that I was able to register in and test: AT&T (3G/4G, no 2G) and T-Mobile (2G/3G/4G). The test results are found below.
I could also see three other 4G networks show up in a network scan (Caprock Cellular, Sprint and Verizon), but none of those were available to me. Presumably neither Tele2 nor Telenor have roaming arrangements with any of those operators.
AT&T - MCCMNC 310410
| Home PLMN | Tech | IPV6 PDP context | IPV4V6 PDP context |
|---|---|---|---|
| Tele2 SE | 3G | Fails (cause code 33) | IPv4-only (cause code 50) |
| Tele2 SE | 4G | Works perfectly | Works perfectly |
| Telenor NO | 3G | Fails (cause code 33) | IPv4-only (cause code 50) |
| Telenor NO | 4G | Works perfectly | Works perfectly |
T-Mobile - MCCMNC 310260
| Home PLMN | Tech | IPV6 PDP context | IPV4V6 PDP context |
|---|---|---|---|
| Tele2 SE | 2G | Fails (cause code 33) | IPv4-only (cause code 50) |
| Tele2 SE | 3G | Fails (cause code 33) | IPv4-only (cause code 50) |
| Tele2 SE | 4G | Works perfectly | Works perfectly |
| Telenor NO | 2G | Fails (cause code 33) | IPv4-only (cause code 50) |
| Telenor NO | 3G | Fails (cause code 33) | IPv4-only (cause code 50) |
| Telenor NO | 4G | Works perfectly | Works perfectly |
3GPP cause code #33 means «requested service option not subscribed», while cause code #50 means «PDP type IPv4 only allowed». The latter doesn’t indicate a fatal error, as I do automatically get a working IPv4-only connection to the Internet.
The fact that IPv6 consistently fails on 2G/3G is in all likelihood due to Tele2/Telenor’s HLR removing the IPv6 capabilities from my subscriber profile before transmitting it to AT&T/T-Mobile’s vSGSN.
Tele2 and Telenor do this to forestall the possible IPv6-related failures described in RFC 7445 sections 3 and 6. In this case, it is in all likelihood an unnecessary precaution, considering that both AT&T and T-Mobile are known to have deployed IPv6 to their own customers.