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Rufnummermitnahme: How to Transfer Your Phone Number Between Carriers in Germany

2024-06-22

Learn how to transfer your German phone number to a new carrier (Rufnummermitnahme) — step-by-step, with real costs, timelines, and mistakes to avoid.

Moving to a better mobile plan in Germany doesn't mean you have to give up the number your friends, family, and employer already know. The process of keeping your number when switching carriers is called Rufnummermitnahme — and while it sounds complicated, it's actually straightforward once you know the steps. Whether you're switching from Telekom to a budget MVNO or from one prepaid SIM to another, this guide walks you through everything.

What Is Rufnummermitnahme and Why Does It Matter?

Rufnummermitnahme literally means "phone number portability" in German. It's the legal right — guaranteed under German telecommunications law (Telekommunikationsgesetz, TKG) — that allows you to keep your existing mobile number when you switch to a different carrier.

For Moroccans living in Germany, this matters a lot. Your phone number is often tied to:

• Your bank account (two-factor authentication via SMS)
• Your German employer or job applications
• Family and friends who already have your number
• Government or Ausländerbehörde correspondence

Losing your number means updating dozens of contacts and services. With Rufnummermitnahme, you avoid that headache entirely — and it costs you nothing extra in most cases.

Which Carriers Support Number Portability in Germany?

Good news: all German mobile carriers are legally required to support Rufnummermitnahme. This includes:

• Major networks: Telekom, Vodafone, O2 (Telefónica)
• Budget brands (MVNOs): Aldi Talk, Lidl Connect, congstar, Blau, WinSIM, freenet, otelo, Klarmobil, simyo
• Discount online carriers: PremiumSIM, Sparhandy, handyvertrag.de

It doesn't matter whether you're on a postpaid contract (Vertrag) or a prepaid SIM — you can transfer your number in either direction.

Important: Portability Only Works Within Germany

You can only port a German mobile number (starting with +49) between German carriers. If you came from Morocco and want to keep a Moroccan number, that's not possible within the German system. Rufnummermitnahme applies exclusively to numbers already registered in the German national numbering plan.

Step-by-Step: How to Transfer Your Number in Germany

Here's how the process works in practice:

Step 1 — Get Your Portability Code (Portierungskennung or KÜN)

Before you can move your number, you need a code from your current carrier. This is called the Portierungskennung (also known as the KÜN — Kundenkennungsnummer).

• Call your current carrier's customer service or log into your online account
• Request the portability code — they are legally required to provide it within 1 business day
• The code is usually valid for 30 days
• Example: Aldi Talk gives you the code via their website under "Mein Konto"; congstar provides it by phone or chat

Step 2 — Sign Up With Your New Carrier

Choose your new plan and sign up. During the registration process, you'll see a field asking whether you want to keep your existing number (usually labeled "Rufnummermitnahme" or "Bestehende Rufnummer mitnehmen").

• Select "Yes" and enter your old phone number
• Enter the portability code (KÜN) you received in Step 1
• Specify the date you want the transfer to happen (or request "as soon as possible")

Step 3 — Cancellation Is Handled Automatically

Here's something many people get wrong: you do not need to separately cancel your old contract. When you initiate a number port, the new carrier sends a transfer request to your old carrier, which simultaneously cancels your old contract or SIM. This is handled automatically under German law.

Exception: If you're on a postpaid contract with a minimum term (Mindestvertragslaufzeit), you may still owe fees until the contract period ends — but the number transfer itself still goes through.

Step 4 — Wait for the Transfer

The actual number transfer typically takes:

• 1–3 business days for prepaid-to-prepaid transfers
• Up to 7 business days for postpaid contracts in some cases

You'll usually receive an SMS or email from both carriers confirming the transfer date. On that date, your old SIM stops working and your new SIM becomes active with your old number.

Step 5 — Keep Your Old SIM Ready During Transition

Don't throw away your old SIM until the transfer is fully confirmed. On the handover day, there may be a window of 1–2 hours where neither SIM works. Keep your phone nearby and test the new SIM as soon as the switch is supposed to happen.

Costs: How Much Does Rufnummermitnahme Actually Cost?

In most cases, Rufnummermitnahme is free. German law prohibits carriers from charging excessive fees for number portability. However, watch for these potential costs:

| Situation | Typical Cost | |---|---| | Portability code (KÜN) from current carrier | Free (legally required) | | Prepaid-to-prepaid transfer | Free (most carriers) | | Postpaid number transfer | Free at new carrier; early termination fees may apply at old carrier | | Activation fee at new carrier | €0–€29.99 (varies by provider; often waived with online signup) |

For example, WinSIM and PremiumSIM frequently run promotions with 0€ activation and free number porting. Aldi Talk charges no porting fee. Even O2 and Telekom do not charge for receiving a ported number.

Watch out for early termination fees (Vertragsstrafe): If you're locked into a 24-month contract with, say, Vodafone, and you port out after 6 months, you may owe the remaining monthly fees. Always check your contract terms before initiating a port.

Rufnummermitnahme for Prepaid SIMs: Special Notes

Many Moroccans in Germany start with a prepaid SIM (like an Aldi Talk or Lidl Connect card) before committing to a longer contract. Here's what you need to know for prepaid-to-prepaid transfers:

• Remaining credit: Any remaining balance on your old prepaid SIM is typically lost when you port out. Spend it down first or accept the loss.
• Validity: Make sure your old SIM is still active (not expired) when you request the port. An expired prepaid SIM cannot be ported.
• Top-up not required: You don't need to top up the old SIM just to initiate the port — as long as it's currently active.

What People Get Wrong About Number Portability in Germany

This is where most confusion and frustration happens. Here are the most common mistakes:

• Cancelling the old contract before porting: Don't do this. Cancel after porting, or let the port cancel it automatically. If you cancel first, you may lose your number.
• Letting the prepaid SIM expire: Prepaid SIMs in Germany deactivate after a period of inactivity (often 12 months without a top-up). Once expired, the number is gone — you can't port it.
• Missing the KÜN validity window: The portability code is only valid for 30 days. If you get the code but wait too long to activate your new SIM, you'll need to request a new code.
• Assuming the number transfers instantly: It won't happen in real time. Plan the switch for a day when you can briefly be unreachable (e.g., a Sunday or day off).
• Forgetting to update 2FA: Once your number is on the new SIM, make sure any SMS-based two-factor authentication (banking apps, email accounts) still works correctly — the SMS will now arrive on the new SIM.
• Not reading the new contract's minimum term: Some cheap plans come with 24-month lock-in periods. If you want flexibility, look for monthly-cancellable (monatlich kündbar) plans.

Conclusion: Keep Your Number, Switch to a Better Deal

Rufnummermitnahme is one of the most consumer-friendly rules in the German telecoms market, and it's something you should use without hesitation when a better plan comes along. The process takes just a few minutes of admin and a few days of waiting — and you walk away with a cheaper plan and the same number everyone already knows.

If you're still in the early stages of your move to Germany and want help navigating SIM cards, Ausbildung applications, or paperwork in general, book a consultation with our German immigration specialist (€16) to plan your move. Our team can help you with everything from your CV builder to your Anschreiben generator so your German journey starts on the right foot.