Keeping your number when you switch provider in Germany: costs, deadlines, steps

What the German Telecommunications Act says about number porting: what it costs, when it is possible and what happens if it takes longer.

All prices in this guide come from our comparison of 274 German mobile tariffs and are average prices per month over 24 months, one-time costs included. As of 18 Oct 2026.

The key points

• Free: you may not be charged directly for porting your number (§ 59(7) of the Telecommunications Act, TKG).
• At any time: for mobile numbers you can request porting at any time, even before your contract ends (§ 59(6) TKG).
• The old contract continues: if you take your number before the contract ends, the old contract stays in place and you keep paying until it ends, then with a new number.
• Fast: the number moves on the day agreed with you, at the latest on the following working day. Your line may not be down for more than one working day during the switch.
• Compensation: if porting is not done on time, you can claim €10 for each day of delay from the provider that caused it.

How the switch works

1. Choose a new tariff, for example in our comparison. When signing up, choose “keep number” (Rufnummer mitnehmen) and enter your number and current provider.
2. Cancel the old contract and ask to take your number with you, or let the new provider cancel for you; many offer this when you order. Name and date of birth must match exactly at the old and the new provider, otherwise porting often fails.
3. Prepaid: there is no contract to cancel. You give your old provider a porting declaration (Verzichtserklärung / Portierungserklärung), usually in your customer account or with a form. You can usually have remaining credit paid out.
4. On the day of the switch neither SIM card works for a short while. After that your number runs on the new card.

Common pitfalls

• Different details at the old and new provider, such as a missing middle name: the most common reason for rejected porting.
• Porting before the contract ends without cancelling: the old contract keeps costing money. Work out whether it is worth it.

Since December 2021 you can cancel contracts after the minimum term with one month’s notice; more in the guide contract, monthly or prepaid.

Legal basis: § 59 of the German Telecommunications Act (provider switching and number porting). This guide is not legal advice.