~tore Tore Anderson's technology blog

IPv6 roaming in Belgium and Romania

I briefly visited Belgium and Romania last month. Using SIM cards from Tele 2 Sweden and Telenor Norway, both of which support the dual-stack IPV4V6 and IPv6-only IPV6 PDP context types, I spent some time testing whether or not I was able to get working IPv6 Internet connectivity while roaming in the various available PLMNs.

In many cases, IPv6-only connection attempts failed completely. Furthermore, dual stack connection attempts more often than not resulted in an IPv4-only Internet connection. Full test results below.

These frequent failures are however not as dramatic as they might sound. Both Tele 2 and Telenor are using a blacklisting trick that blocks their subscribers from using IPv6 when roaming in certain operators (whose IPv6 capabilities hasn’t yet been verified). See RFC 7445 section 3 and section 6 for technical details on how this trick works. When roaming in an operator blacklisted in this manner, IPv6-only connection attempts made in 2G/3G coverage will fail with 3GPP cause code 33 (requested service option not subscribed), while dual stack connection attempts will result in IPv4-only Internet connectivity.

The good news is that when my devices were set up to request dual-stacked IPV4V6 PDP contexts, they would in every single case get at least the same level of Internet connectivity as they would when requesting an IPv4-only IP PDP context; having the devices request dual-stacked connectivity had no downside whatsoever.

I’ve also performed the same kind of IPv6 roaming testing in Sweden a while back.

Test results

Belgian PLMNs

Proximus - MCCMNC 20601

Home PLMN Tech IPV6 PDP context IPV4V6 PDP context
Tele 2 Sweden 2G Fails (cause 33) IPv4-only connection
Tele 2 Sweden 3G Fails (cause 33) IPv4-only connection
Telenor Norway 2G Works perfectly Works perfectly
Telenor Norway 3G Works perfectly Works perfectly

I was not able to test in 4G/LTE coverage, as it appears that neither Tele 2 nor Telenor have a 4G/LTE roaming agreement with Proximus.

Tele 2 is applying the blacklisting trick described above. Telenor, on the other hand, does not and IPv6 works perfectly.

Orange - MCCMNC 20610

Home PLMN Tech IPV6 PDP context IPV4V6 PDP context
Tele 2 Sweden 2G Fails (cause 33) IPv4-only connection
Tele 2 Sweden 3G Fails (cause 33) IPv4-only connection
Telenor Norway 2G Fails (cause 33) IPv4-only connection
Telenor Norway 3G Fails (cause 33) IPv4-only connection

In the Orange PLMN I got identical behaviour with both my SIM cards. It appears both Tele 2 and Telenor are blacklisting, and there is no 4G/LTE roaming agreement.

As with Tele 2/Proximus, dual stack «works» in the sense that I get IPv4-only Internet connectivity.

BASE - MCCMNC 20620

Home PLMN Tech IPV6 PDP context IPV4V6 PDP context
Tele 2 Sweden 2G Fails (cause 33) IPv4-only connection
Tele 2 Sweden 3G Fails (cause 33) IPv4-only connection
Tele 2 Sweden 4G Works perfectly Works perfectly
Telenor Norway 2G Fails (cause 33) IPv4-only connection
Telenor Norway 3G Fails (cause 33) IPv4-only connection
Telenor Norway 4G Works perfectly Works perfectly

BASE demonstrates how the blacklisting trick only works on 2G/3G and not on 4G. Both Tele 2 and Telenor are blacklisting here, but nevertheless dual stack and IPv6-only works perfectly if the data PDP context is established while in 4G coverage.

Romanian PLMNs

Vodafone - MCCMNC 22601

Home PLMN Tech IPV6 PDP context IPV4V6 PDP context
Tele 2 Sweden 2G Fails (cause 32) IPv4-only connection
Tele 2 Sweden 3G Fails (cause 32) IPv4-only connection
Tele 2 Sweden 4G Fails (cause 32) IPv4-only connection
Telenor Norway 2G Fails (cause 32) IPv4-only connection
Telenor Norway 3G Fails (cause 32) IPv4-only connection
Telenor Norway 4G Fails (cause 32) IPv4-only connection

Vodafone is an interesting case. The fact that IPv6 and dual stack fails on 2G and 3G with 3GPP cause code 32 (service option not supported) instead of 33, and the fact that it also fails in the same way on 4G/LTE, indicate that this is not caused by the blacklisting trick. Instead, it would appear that Vodafone is deliberately blocking visitors from using of IPv6 on their network.

For operators such as Tele 2 and Telenor, this is not such a big deal, as dual-stack still «works» by falling back on IPv4-only connectivity. Operators using 464XLAT, on the other hand, will likely find Vodafone’s behaviour hugely problematic.

Telekom - MCCMNCs 22603 (2G) and 22606 (3G)

Home PLMN Tech IPV6 PDP context IPV4V6 PDP context
Tele 2 Sweden 2G Fails (cause 33) IPv4-only connection
Tele 2 Sweden 3G Fails (cause 33) IPv4-only connection
Telenor Norway 2G Fails (cause 33) IPv4-only connection
Telenor Norway 3G Fails (cause 33) IPv4-only connection

Identical results as with Orange in Belgium. I was unable to get 4G/LTE coverage, and both Tele 2 and Telenor applies blacklisting on 2G/3G.

Digi.Mobil - MCCMNC 22605

Neither Tele 2 nor Telenor seems to have any form of roaming agreement with this operator, at least I was completely unable to register in their network, and thus unable to perform any IPv6 testing.

Orange - MCCMNC 22610

Home PLMN Tech IPV6 PDP context IPV4V6 PDP context
Tele 2 Sweden 2G Fails (cause 33) IPv4-only connection
Tele 2 Sweden 3G Fails (cause 33) IPv4-only connection
Telenor Norway 2G Works perfectly Works perfectly
Telenor Norway 3G Works perfectly Works perfectly
Telenor Norway 4G Works perfectly Works perfectly

Tele 2 does not appear to have a 4G/LTE roaming agreement with Orange, and the blacklisting trick is being used on 2G/3G.

With Telenor, on the other hand, there’s no blacklisting and both IPv6-only and dual stack works perfectly on all technologies.