How do you port a German mobile number in 2026?

What do you need before porting your German mobile number?

Active old SIM · Kundennummer · IBAN · Ausweis · New operator decision

Five items. Your old SIM must stay active until the port completes — if you cancel it first, the port fails. You need your old Rufnummer, the Kundennummer from the old operator (PUK is not enough), a German IBAN, a valid passport or EU ID for the new operator’s ident check, and the new tariff already picked. Allow two days between ordering and the port date.

Most porting failures trace to one of two errors. The first is cancelling the old contract before the new operator triggers the port — once your old number is deactivated, the new operator has nothing to pull across, and you end up with a fresh number you did not want. The second is a mismatch between the Kundennummer you typed into the form and the one the old operator has on file. Telekom, Vodafone, O2, congstar, ALDI TALK, and 1&1 all store this number in their app under Vertragsdaten or on any monthly bill (Rechnung). Copy it exactly, including leading zeros.

Source: Bundesnetzagentur Rufnummernportierung guidance, operator signup flows, verified May 2026

How does German Rufnummermitnahme work?

Gaining operator drives · Losing operator releases · Database update · Live cutover

Rufnummermitnahme is operator-to-operator, not customer-driven. The new operator (the “gaining” carrier) submits a porting request to the old one (the “losing” carrier) through a clearinghouse called the Zentrales Datenbankregister. The losing operator verifies you are the line holder, releases the number, and the cutover happens at a scheduled moment — typically the morning of the agreed date, with the old SIM going dark and the new SIM activating within minutes.

Under the Telekommunikationsmodernisierungsgesetz (effective 1 December 2021), the porting workflow was tightened in three ways: the fee cap was abolished (it is now free), the maximum porting window was set to one working day from the requested date, and operators became liable for compensation if they cause a delay. Practically that means a working-day port: order Monday, port Tuesday morning. Weekend orders execute on the next working day.

You retain your Rufnummer for free for as long as you keep at least one German SIM. The number itself is not yours — the Bundesnetzagentur assigns it to the operator block — but the right to carry it across operators is enshrined in § 59 TKG. You can port the same number multiple times (e.g. Telekom → congstar → O2) at no charge.

How do you port your German number in 5 steps?

Order new SIM · Fill the Rufnummermitnahme form · Wait · Cutover · Old contract closes

Five steps, roughly 20 minutes of your time spread over one to two working days. The new operator does the heavy lifting — you only fill in a short Rufnummermitnahme form during signup, verify your identity (PostIdent or VideoIdent), wait one working day, and then the new SIM (or eSIM) goes live on your old number. The old contract terminates automatically on the porting date if you are out of minimum term, or on its next regular end-date if you are mid-term.

1. Order the new SIM and pick a porting date. Choose the new tariff at Telekom, Vodafone, O2, congstar, ALDI TALK, 1&1, fraenk, or any MVNO. During signup, tick “Rufnummermitnahme” (sometimes labelled “Ich möchte meine Rufnummer mitnehmen”). You can request the port for the next working day, a specific date, or the end of your old contract term. (eSIM and physical SIM follow the same flow)
2. Fill out the Rufnummermitnahme form with the old SIM details. Enter the old Rufnummer (full +49 format), the old operator name, your Kundennummer / Vertragsnummer, and the address registered on the old contract. Most signup flows show this as a 30-second sub-form in the cart.
3. Verify your identity (PostIdent or VideoIdent) and pay. Required by BNetzA for any new German SIM. VideoIdent runs through the operator’s app with a passport or EU ID and takes 5–10 minutes. PostIdent uses a Deutsche Post branch and takes 1–3 days. SEPA-Lastschrift covers the recurring bill. (See our VideoIdent guide)
4. Wait one working day — the new operator handles the rest. The gaining operator submits the port through the Zentrales Datenbankregister, the losing operator releases the number, and cutover is scheduled. Keep the old SIM in a phone so you can still take calls until the moment of port.
5. Insert the new SIM (or scan the eSIM QR), test, and stop using the old one. On the scheduled morning, the old SIM loses signal and the new SIM picks up your number within minutes. Place a test call and send a test SMS to confirm. The old contract auto-terminates — you may receive a final invoice for any partial billing period. (typical cutover gap: under 25 minutes)

Is German number porting free in 2026?

Free since 1 December 2021 · Previous €7 cap removed by TKG-Novelle

Yes. Porting is free by law since the Telekommunikationsmodernisierungsgesetz (TKG-Novelle) took effect on 1 December 2021. Before that, operators could charge a one-off fee of up to €6.82. After that, § 59 TKG bans any porting charge to the customer — the new and old operators settle costs between themselves. Any operator still invoicing a porting fee in 2026 is non-compliant and Bundesnetzagentur will refund it.

Source: Bundesnetzagentur, § 59 TKG, verified May 2026

One quiet exception: a few operators still bill a small “Bereitstellungspauschale” (activation fee, €10–40) when you sign the new contract. That is not a porting fee — it is a setup charge for the new SIM, which is still legal. If it appears on the invoice line item as a porting cost, dispute it. Telekom, Vodafone, O2, congstar, ALDI TALK, fraenk, and 1&1 currently all advertise Rufnummermitnahme as cost-free.

What if porting fails?

Mismatch · Cancelled old SIM · Wrong customer number · BNetzA complaint

Three failure modes account for roughly 90% of stalled ports: a Kundennummer mismatch, an old SIM already cancelled, and a name/address mismatch between contracts. The new operator will email you (and sometimes SMS) within 48 hours if the port is rejected. Most fixes are a corrected form resubmission. As a last resort, file a complaint with Bundesnetzagentur — they adjudicate disputes within 4–6 weeks.

• Kundennummer mismatch. The most common rejection. Open the old operator’s app, copy the Kundennummer exactly (10–12 digits is typical), resubmit the form. Some operators distinguish Kundennummer (account) from Vertragsnummer (per-line) — use the Vertragsnummer for the specific Rufnummer.
• Old contract already terminated. If you cancelled before triggering the port, the line is gone. You cannot recover the number. Order without porting and accept a new Rufnummer, or contact the old operator within 30 days of termination to request reactivation — some allow it, most do not.
• Name or address mismatch. If you moved house since signing the old contract and did not update the address, the data will not match. Update the address with the old operator first, wait 24 hours, then resubmit the porting form.
• Number not portable. A handful of legacy 0700/0900 numbers and certain corporate SIP trunks are not portable. Standard mobile (015x, 016x, 017x) and fixed (030x, etc.) numbers are always portable.
• Operator delay past 1 working day. File the compensation claim. Under § 59 (4) TKG you are entitled to €5–20 per delayed day from the new operator. Email Kundenservice with the porting reference and the missed date.
• Stuck longer than 2 weeks. File a complaint with Bundesnetzagentur at bundesnetzagentur.de/verbraucherservice. Include the porting reference, both operators’ correspondence, and the desired remedy.

Can you port a contract (Vertrag) mid-term?

Number ports any time · Contract obligations stay · 4-week notice rule

Yes — the number ports any time, but you still owe the remaining months of the old contract. Porting and contract termination are two separate things. You can move your Rufnummer to a new operator mid-term, keep paying the old base fee until the minimum term ends, and then the old contract auto-terminates. If you are out of minimum term, send a Kuendigung letter respecting the 4-week notice rule and the porting closes the contract on the same date.

Here is the practical mechanic. Most German mobile contracts run a 24-month minimum term with a 4-week notice period at the end. Once you are past the 24 months, you can terminate any time with 4 weeks’ notice (since 1 December 2021, under the same TKG-Novelle). Inside the minimum term, you remain liable for the base fee even after the port. Two scenarios:

• Past minimum term, 4-week notice. Order the new SIM, request porting for the end of the 4-week notice window, send the Kuendigung letter to the old operator before then. Both close on the same day. This is the clean path.
• Inside minimum term. You can still port the number now, but the old contract keeps charging the monthly base fee until the term ends. You will pay both contracts until the minimum term lapses. Worth doing only if the new tariff is materially cheaper or your old plan has stopped working for you.
• Sonderkuendigungsrecht. A few scenarios let you exit the contract early at no penalty: the operator raised prices outside what the contract allowed, you moved abroad permanently, or coverage at your registered address dropped below contract level. Cite the specific reason in the Kuendigung letter.

Should you keep your number or get a new one?

Continuity · Speed · Privacy · 2FA risk

Keep it in 95% of cases. Porting is free, takes one working day, and a German mobile number is wired into your banking 2FA, SCHUFA, Anmeldung, employer payroll, and every German contract you have. The case for a new number is narrow: you want fresh signups with no spam history, you moved out of Germany and will not return, or you are switching to prepaid for privacy after a contract was tied to your name.

The friction of changing a German mobile number is concentrated in two places. First, every bank that uses SMS-TAN (DKB, Sparkasse, Volksbank, ING, comdirect) requires a written update with passport copy — expect 1–2 weeks of TAN downtime per bank. Second, government services tied to your number (ELSTER, Krankenkasse SMS alerts, Buergeramt appointment confirmations) all need manual updates. By contrast, porting carries all of that across automatically.

Source: SimCompare365 editorial guidance, May 2026