Prepaid SIM cannot connect to any network abroad (roaming enabled, multiple countries tested)

Daniel2424

Hello,

I’m currently experiencing an issue with congstar prepaid SIM cards when roaming abroad.

Situation:

The SIMs are used outside Germany (tested in Vietnam and China)
Devices: iPhone and Android (multiple devices tested)

Observed behavior:

Roaming is enabled on the device
Available networks (e.g. Viettel, Mobifone, etc.) are visible
However, the SIM cannot connect to any network (“No Service” / registration fails)
Manual network selection also does not work
Same issue occurs across multiple countries

What I have already tried:

Enable/disable roaming
Restart device
Manual network selection
Test SIM in different devices

Question:

Is roaming enabled for congstar prepaid SIMs in countries like Vietnam or China?
Could there be a roaming block or missing activation on the SIM/account?
Does the SIM need to be activated in Germany first before roaming works?

Any help would be appreciated. Thank you!

harob

Hi Daniel2424

was the SIM activated in Germany and did you have a connection in Germany?

For prepaids there's normally no roaming-blockage possible.

For usage outside of Germany (outside EU) you have to activate a datapass. For china you can choose one of the following passes:

And for Vietnam:

All together: The SIM has to be activated before first use. Normally it can bet also activated outside of Germany - but it has to be activated by using your passport (e.g. Video-Ident / Post-Ident).

Patrick

Hallo Daniel2424 ,

The thing is, for countries like China or Vietnam, you need to book data passes for Country Group 3. You can do this on-site via “datapass.de”.

Once you've booked that, select one of our partner networks for China (China Mobile, China Unicom, or China Telecom).

Then mobile data should be available.

Best regards, Patrick

https://www.congstar.de/hilfe-service/roaming/?country=China&targetCountry=Deutschland&group=non-eu&useCase=tarif-im-ausland-nutzen&tariff=postpaid

Daniel2424

Hi,

Thanks for the reply.

To clarify the situation: I’m not fully sure whether the SIM was successfully activated in Germany. A friend brought it to Vietnam for me and mentioned that the KYC (Video-Ident) was completed.

However, the current behavior is:

the SIM can detect available networks (e.g. Viettel, Mobifone)
but it cannot connect to any network at all (no service / registration fails)

Based on this, I believe the issue might not be related to datapasses (since even basic network registration fails), but rather a possible activation or provisioning issue.

Could you please check if the SIM is fully activated and allowed to register on foreign networks?

Phone number: +49 xxxxxxx234

Thanks!

Flosse08

Daniel2424 I censored your phone number in the public part. Please put your phone number in the forum profile. Add also your customer data in the forum profile together with the legitimation pin. Then the congstar support can have a look if every thing is ok with the activation of the SIM card.

Stephanie

Hi Daniel2424

we can check this. But for that we need your customer number, full Name and the Legi Pin (Important: not the Sim PIN). If you don't know your Pin, then send us with our Formular a copy from the ID-Card of the SIM card contract holder. Please fill in the missing information in your forum profile and never post it publicly.

Greets Stephanie