If you are in need of a phone number for use in Germany, you can definitely check out Telekom Deutschland (Germany's T-Mobile, owned by Deutsche Telekom, owners of T-Mobile US).
You can definitely become a T-Mobile US customer once you come back to the United States. If you need help with any T-Mobile US-related issues or questions, you can always contact T-Mobile using the contact us page. Please keep in mind, I'm not a T-Mobile representative.
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