Comment 6 for bug 1499342

Interesting. Indeed, a scan on the command line reveals this

Scanning operators on modem /ril_0...
[ /ril_0/operator/26203 ]
    MobileCountryCode = 262
    MobileNetworkCode = 03
    Name = simyo
    Status = current
    Technologies = gsm umts

[ /ril_0/operator/26202 ]
    MobileCountryCode = 262
    MobileNetworkCode = 02
    Name = Vodafone.de
    Status = forbidden
    Technologies = gsm umts

[ /ril_0/operator/26207 ]
    MobileCountryCode = 262
    MobileNetworkCode = 07
    Name = o2 - de
    Status = forbidden
    Technologies = gsm umts

[ /ril_0/operator/26201 ]
    MobileCountryCode = 262
    MobileNetworkCode = 01
    Name = T-Mobile D
    Status = forbidden
    Technologies = gsm umts

This is weird though as I did get an email from them the day national roaming was activated, explicitly stating that it would be enabled for me. I'll try this SIM card in other devices, seeing if I can get it to work at all with it.