Mobile Phone and SIM Contracts in Germany

A German mobile plan usually starts with one practical choice: Prepaid or contract? After that, the important questions are identity verification, data allowance, minimum term, cancellation and whether you want to keep your number later.

Quick answer

With Prepaid, you pay for credit or a package before using it. With a Laufzeitvertrag, you enter an ongoing contract with recurring charges and defined conditions. The exact tariffs are provider-specific, but the consumer rules for telecom contracts are not.

Before a standard consumer telecom contract is concluded, the provider must give you a clear Vertragszusammenfassung. The initial contract term may not exceed 24 months, and providers must also offer a contract with an initial term of no more than 12 months. After a silent renewal beyond the initial term, you can terminate with one month’s notice.

For prepaid mobile services, the provider must verify required identity data before activation.

1. Prepaid or Laufzeitvertrag?

The best format depends on how you use your phone, not on a universal “best German provider.”

Prepaid can be useful if you want:

• no long minimum term
• spending controlled through prepaid credit/packages
• a simple first SIM after arrival

Laufzeitvertrag can be useful if you want:

• a recurring monthly tariff
• a defined monthly data/voice package
• optional device or service bundles, depending on the provider

Do not assume a contract is cheaper or prepaid is always more flexible. Compare the actual monthly cost, data allowance, term, activation charge and cancellation conditions.

2. Prepaid SIMs require identity verification before activation

Germany does not allow anonymous activation of standard prepaid mobile services.

Under § 172 TKG, providers of prepaid mobile services must verify the correctness of the required name/date-of-birth data before activation using an accepted identity document or another approved identification procedure. The law lists documents such as a German identity card, passport, certain official foreign identity documents and residence titles.

The Bundesnetzagentur separately regulates which alternative identification procedures providers may use.

So if a prepaid SIM says Identifizierung erforderlich, that is a normal legal activation step. Do not send identity documents to an unverified third party outside the provider’s legitimate process.

3. Read the Vertragszusammenfassung before agreeing to a mobile contract

The same consumer contract-summary rules that apply to fixed-line telecom services also matter for mobile contracts.

The summary should show key information such as:

• essential services
• prices
• activation charges
• contract duration
• renewal and cancellation conditions
• internet-access information where relevant

If you agree to a telecom contract by telephone, the Bundesnetzagentur explains that it only becomes effective after the provider sends the contract summary and you approve the contract in text form, for example by email.

4. Check data volume, speed wording and what happens after the allowance is used

The word Datenvolumen is central to mobile offers.

Before signing, check:

• how much high-speed data is included
• what happens after the allowance is used
• whether speed is reduced or additional usage is charged
• what the contract says about estimated maximum mobile speed
• whether calls/SMS and roaming are included in the situations you need

These details are tariff-specific, so rely on the provider’s current product information and contract summary rather than a general guide.

5. Know the maximum initial term and what happens after it

Under § 56 TKG:

• the initial term for the relevant consumer telecom contract may not exceed 24 months
• the provider must also offer a contract with an initial term of no more than 12 months
• after a silent renewal beyond the initial term, the customer can terminate with one month’s notice

If a tariff includes a phone or other device, read the device-payment terms separately. A service contract and device financing can create different payment obligations.

6. Online and telephone contracts can have a withdrawal right

The Bundesnetzagentur notes that certain telecom contracts concluded online, by telephone or otherwise at a distance/outside business premises can have a statutory 14-day Widerrufsrecht, subject to the legal conditions. A purchase made in a physical shop generally does not automatically have the same statutory right just because you change your mind.

If you need to withdraw, use the provider’s current withdrawal information and act within the applicable period.

7. Keeping your number: Rufnummernmitnahme

If you change mobile provider, you can usually take your existing number with you.

Under § 59 TKG and Bundesnetzagentur guidance:

• number portability may not be charged directly to the end user
• after contract end, you can request porting for up to one month
• with mobile numbers, you can request portability even before the old contract ends
• taking the number early does not end the old contract: the old contract continues, and the old provider can assign a new number for the remaining term

This last point is easy to miss: number porting and contract cancellation are not the same process.

8. Make sure your personal data match when you port a number

The Bundesnetzagentur advises that the customer data in the old and new provider records should match for number portability, including the relevant name and other identifying contract data.

If a port fails, check the spelling and contract-holder details before assuming the number is lost.

9. New in 2026: official mobile performance evidence

Since 20 April 2026, the Bundesnetzagentur has had a binding procedure for proving qualifying mobile internet underperformance and provides the free “Breitbandmessung Nachweisverfahren Mobilfunk” app.

For the standard proof campaign, the Bundesnetzagentur’s 2026 rules use 30 measurements across five calendar days, six measurements per day, following the app’s requirements.

If the official process proves a qualifying significant, continuous or regularly recurring deviation, § 57 TKG can support a right to reduce the price or terminate extraordinarily.

Do not confuse ordinary signal variation in one location with a legally proven Minderleistung. Use the official procedure if you want to assert a formal right.

10. If you use an eSIM, the contract rules still matter

An eSIM is a digital SIM profile rather than a removable plastic card. Availability and activation steps vary by provider and device.

The important point is that “eSIM” does not remove the normal questions about tariff, identity, term, data allowance, cancellation and number portability.

Common mistakes to avoid

• Buying a prepaid SIM and being surprised that identification is required before activation.
• Accepting a mobile contract without saving the Vertragszusammenfassung.
• Confusing number portability with cancellation of the old contract.
• Assuming every 24-month offer is the only term the provider may offer.
• Ignoring what happens after the monthly data allowance is used.
• Using informal speed tests as if they were the official 2026 mobile evidence procedure.

Frequently asked questions

Do I need identification for a prepaid SIM in Germany?

Yes. Providers of prepaid mobile services must verify the required identity data before activation using the methods allowed under § 172 TKG and Bundesnetzagentur rules.

Can a mobile contract have a 24-month minimum term?

Yes, an initial term of up to 24 months is allowed, but the provider must also offer consumers a contract with an initial term of no more than 12 months.

Can I keep my mobile number when changing provider?

Yes. Number portability is protected under § 59 TKG, and providers may not charge the end user a direct porting fee.

Can I port my mobile number before the old contract ends?

Yes. Mobile customers can request portability before the old contract ends, but the old contract itself remains in force. The old provider can assign a new number for the remaining contract period.

Is there a legal way to prove bad mobile internet speed now?

Yes. Since 20 April 2026, the Bundesnetzagentur has a binding mobile evidence procedure and a dedicated free app. If the official process proves a qualifying deviation, consumer rights under § 57 TKG may apply.

Does eSIM mean I do not need a normal mobile contract?

No. eSIM changes the technical SIM format, not the need to understand the tariff, activation, contract term, data allowance and cancellation conditions.

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