Rufnummernmitnahme — Number Portability
Rufnummernmitnahme is the legal right to retain your mobile phone number when switching operators. It is guaranteed under German telecommunications law (Telekommunikationsgesetz, TKG §46) and European Union regulatory requirements.
The number portability process is initiated by the receiving operator (the one you are switching to), not the losing operator. The receiving operator requests the number transfer on your behalf after verifying your identity and that you hold the number with the current operator.
Legal Framework
The Telekommunikationsgesetz (TKG) of 2021 (updating the 2004 law to implement the European Electronic Communications Code) defines the rules for mobile contract formation, portability, and termination in Germany:
- Maximum initial contract term: 24 months (2-year contracts)
- Notice period after initial term: Maximum 1 month (reduced from 3 months by the 2021 TKG reform)
- Auto-renewal term: Maximum 1 month (previously up to 12 months)
- Number portability completion: Must be completed within 1 working day from the agreed transfer date
The 2021 TKG reform significantly improved consumer rights by shortening auto-renewal periods and reducing notice requirements.
Kündigungsfristen — Notice Periods
Notice periods depend on your contract type and when the initial contract term expires:
| Contract Stage | Notice Period Required | Notes |
|---|---|---|
| Within initial 24-month term | As specified in contract | Early termination fees may apply |
| At end of initial term | 1 month (maximum) | Applies since TKG 2021 reform |
| After initial term (rolling monthly) | 1 month | Month-to-month rolling |
| Prepaid (Prepaid card) | None (no commitment) | No porting notice required |
When a portability request is made through the new operator, the receiving operator and the losing operator coordinate the transfer date to respect the contractual notice period. Your service with the current operator continues until the transfer date.
Portability Process — Step by Step
- Compare coverage: Use the Bundesnetzagentur atlas and operator maps to verify the new operator provides adequate coverage at your regular locations.
- Choose a new plan: Select a tariff from the new MNO or MVNO that meets your data, call, and roaming requirements.
- Request portability: During the contract signup with the new operator, indicate that you want to transfer your existing number. You will need to provide your current phone number and, in some cases, your customer number from the current operator.
- Identity verification: Complete the PostIdent or VideoIdent process required by German telecommunications law for new SIM activation.
- Agree on transfer date: The new operator submits the portability request specifying a transfer date that respects your current contract's notice period.
- Receive new SIM or eSIM: The new operator sends a physical SIM or eSIM activation credentials.
- Transfer day: On the agreed date, typically at midnight, your number is ported. The new SIM activates. The old SIM deactivates. Maximum interruption: 2 hours.
eSIM Migration in Germany
All three German MNOs support eSIM for qualifying devices. An eSIM (embedded SIM) eliminates the physical SIM card and allows operator profiles to be downloaded digitally. For switching with an eSIM:
- The new operator provides a QR code or activation code to install their eSIM profile
- Number portability works identically with eSIM — the process is the same as with a physical SIM
- Devices can hold multiple eSIM profiles simultaneously, but only one can be active at a time for mobile data
- iPhone 14 and later (US models) are eSIM-only; European models retain a physical SIM slot alongside eSIM
Some MVNOs in Germany do not yet support eSIM. Verify eSIM availability before choosing a plan if you want to use this feature.
What to Check Before Switching
- Coverage at home and work: Check both the operator map and the Bundesnetzagentur atlas.
- Coverage on your regular travel routes: If you travel by train or car in rural areas, verify coverage along those routes.
- VoLTE support: Ensure the new operator and your device support Voice over LTE. Without VoLTE, you may lose call quality on 4G-only networks where 2G/3G has been shut down.
- Roaming terms: Check EU roaming rules and any international roaming tariffs if you travel outside Germany.
- Contract term and porting costs: Confirm there are no porting fees (prohibited under TKG since 2021) and understand any early termination conditions.
- Device compatibility: Verify your device supports the frequency bands used by the new operator, particularly for 5G.
Switching to a Mobile Virtual Network Operator (MVNO)
MVNOs (Mobile Virtual Network Operators) use one of the three MNO networks without operating their own radio infrastructure. German MVNOs include providers such as congstar (Telekom network), Aldi Talk (Telefónica/O2 network), Freenet, klarmobil, and others.
Switching to an MVNO involves the same portability process as switching to an MNO. Coverage is identical to the host network unless the MVNO agreement excludes certain network features (such as 5G or LTE in specific scenarios — verify before signing).
Frequently Asked Questions
How long does the number portability process take?
Under German law (TKG §46), the transfer must be completed within one working day from the agreed transfer date. In practice, the transfer typically occurs at midnight on the scheduled date, with a brief service interruption of up to 2 hours while the switch completes.
Can I keep my number if switching from a postpaid to a prepaid plan?
Yes. Number portability applies regardless of whether the source or destination is postpaid or prepaid. The process is the same, though prepaid-to-postpaid switching may involve a different identity verification step.
Is there a charge for number portability in Germany?
No. The 2021 TKG reform prohibits operators from charging a fee for Rufnummernmitnahme. Any contract clause attempting to impose such a charge is invalid.
What happens to my old SIM card after porting?
The old SIM card is deactivated on the transfer date. Any remaining balance on a prepaid card is typically forfeited unless specific contractual terms provide for a balance refund (uncommon). Physical SIM cards should be disposed of securely.